JPH0737974B2 - Organic carbon measuring device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an organic carbon measuring device for measuring total organic carbon contained in industrial wastewater, lake water, seawater, river water, etc. The present invention relates to an organic carbon measuring device that can measure even a small amount with high accuracy.

[Conventional technology]

Conventional devices of this type convert total carbon contained in sample water into carbon dioxide, determine the total carbon in the sample water by quantifying the carbon dioxide, and then convert the inorganic carbon contained in the sample water to carbon dioxide. It is converted into carbon, and this carbon dioxide is similarly quantified to obtain inorganic carbon, and the organic carbon is obtained from the difference between the two.

Combustion furnaces are used to convert all carbon to carbon dioxide. This combustion furnace is filled with a catalyst such as a platinum catalyst, and a certain amount of sample water injected into the combustion furnace is allowed to pass through a packed bed heated to 650 to 950 ° C at a predetermined space velocity together with a carrier gas. Thus, among all the carbon, organic carbon is burned to be converted into carbon dioxide, and carbon salts and hydrogen carbonates which are inorganic carbon are thermally decomposed and converted into carbon dioxide. In addition to carbon dioxide, water vapor was contained in the combustion products, and this was coagulated and removed by a drain separator attached after the combustion furnace.

On the other hand, a reaction furnace is used to convert inorganic carbon into carbon dioxide. As a reactor, for example, Japanese Patent Publication No. Sho 52-2036
There is one disclosed in Japanese Patent No. 0. This type of reaction furnace is filled with a quartz glass particle carrier or the like coated with phosphoric acid, and the phosphoric acid and the inorganic carbon carbonate or hydrogencarbonate are charged.
Reaction around 150 ℃ (eg Na ₂ CO ₃ + H ₃ PO ₄ → Na ₂ HPO ₄ + CO ₂
+ H ₂ O) to convert to carbon dioxide.

Each oxygen dioxide generated in this way, flows into a gas detection unit connected to the downstream side of the reaction furnace, for example, a non-dispersion type infrared gas analyzer, is subjected to infrared analysis, and has a carbon dioxide concentration obtained. Quantification was performed by obtaining the peak height or peak area of the corresponding peak signal. When carbon dioxide is quantified, the quantified carbon dioxide is determined from the graph of the relationship between carbon dioxide peak height or peak area and total carbon concentration (linear equation), which was obtained from the prepared standard solution of total carbon. The total carbon concentration in the carbon-based sample is determined.

As described above, the conventional organic carbon measuring device is composed of a carrier gas supply unit for supplying a carrier gas, a combustion furnace, a reaction furnace, and a gas detection unit, which are sequentially connected from the upstream portion to the downstream portion of the carrier gas by a communication pipe. It is connected in series. The carrier gas used does not substantially contain carbon dioxide, and, for example, highly purified air or nitrogen is often used.

[Problems to be Solved by the Invention]

Although conventional organic carbon analyzers are certainly effective in measuring organic carbon contained in industrial wastewater, lake water, etc., the sample water actually collected contains a wide variety of organic and inorganic substances. However, some of the problems remain, since the combustion product gas may contain a corrosive component or the like, or a component that interferes with the reaction in the reaction furnace.

That is, corrosive components such as hydrochloric acid and nitric acid are generated in the sample water containing a large amount of acids and salts in the combustion furnace, and if these are not removed reliably, they will corrode the measurement cell of the gas detection unit and cause measurement errors. However, it produces a spectrum that interferes with the absorption spectrum of carbon dioxide, which gives an error in the measurement of carbon dioxide.

In addition, since the reaction furnace for measuring inorganic carbon is used by raising the temperature to around 150 ° C, it can be easily heated in samples containing easily oxidizable components in lower carboxylic acids such as oxalic acid and malic acid. It decomposed and produced carbon dioxide, which caused an error in the quantitative value of inorganic carbon.

Furthermore, since the temperature of the reactor is raised to around 150 ° C, samples such as seawater that contain a large amount of salts such as sodium chloride react with phosphoric acid (NaCl + H ₃ PO ₄
→ NaH ₂ PO ₄ + HCl) to generate an acid, similar to the above
It caused corrosion and measurement error.

Further, in order to accurately measure a sample containing only a small amount of inorganic carbon, a large amount of sample must be used. However, in a conventional reaction furnace, when a large amount of sample, for example, 200 μm or more, is injected, phosphoric acid in the packed bed flows out into the sample and causes a decrease in the temperature of the packed bed. The peak signal tailing of carbon dioxide was remarkable and accurate measurement was difficult, and the injection volume of the sample was limited to 200μ.

The present invention has been made to solve the above problems, even if the sample water contains a large amount of acid and salts, and even if the sample water contains only a small amount of inorganic carbon, It is an object of the present invention to provide an organic carbon measuring device capable of accurately measuring inorganic carbon.

[Means for Solving the Problems]

The organic carbon measuring device according to the present invention comprises a combustion unit for injecting sample water to combust or thermally decompose organic carbon and inorganic carbon to convert all of these carbons into carbon dioxide, and inject the sample water for inorganic treatment. A reaction part for reacting carbon to convert it to carbon dioxide and each of the carbon dioxides are individually detected and quantified, and the total carbon and the inorganic carbon are calculated, and the organic carbon is measured from the difference between the total carbon and the inorganic carbon. In the organic carbon measuring device according to the above, the combustion part is connected to a collection part containing a collection liquid, and the combustion product gas from the combustion part is bubbled to purify the combustion product gas. The collection part is provided with a sample water injection port, and the sample water is injected through the injection port together with an acid at appropriate times, and the collection part is configured as a reaction part for converting inorganic carbon into carbon dioxide in an acidic aqueous solution. It was done.

For the same purpose, a solid acid may be stored in the collection part instead of the collection liquid.

[Action]

According to the present invention, when measuring a total carbon, when a sample is injected into the combustion section, the total carbon is converted into carbon dioxide and bubbled in the collection section together with other water vapor etc., and only carbon dioxide is detected along with the gallery gas in the detection section. When the amount of carbon dioxide is quantified, and when measuring inorganic carbon, the sample is injected with the acid from the inlet of the collection part in a timely manner, it is decomposed in the collection liquid and converted into carbon dioxide and reaches the detection part. , The amount of carbon dioxide is quantified, and the organic carbon can be measured by subtracting the school building (inorganic carbon) from the former (total carbon).

When the solid acid is stored in the collection unit, this solid acid is ion-exchanged with cation ions such as hydrogen carbonate in the sample, and the carbon dioxide generated at this time can be easily bubbled with a carrier gas. Convert to carbon dioxide. Moreover, this solid acid is easily regenerated by the acids in the combustion product gas.

〔Example〕

 The present invention will be described below based on illustrated embodiments.

FIG. 1 is a schematic diagram showing the configuration of the apparatus of this embodiment. As shown in the figure, the organic carbon measuring apparatus includes a carrier gas supply unit (1) for supplying a carrier gas and a combustion furnace (3) connected to the carrier gas supply unit (1) through a pipe (2). ), A collection part (5) communicated with the combustion furnace (3) through a connecting pipe (4), and a collection part (5) communicated with the collection part (5) through a pipe (6) to detect carbon dioxide. And a recording unit (8) for recording the detection result of the carbon dioxide detection unit (7) as a graph. Further, the pipe (6) connecting the collection part (5) and the detection part (7) forms a U-shaped pipe part (6a) in the middle as shown in the figure, and the gas flowing through this pipe (6) is The water is condensed by passing through a dehumidifying section (9) for cooling and dehumidifying the condensed water, and the condensed water is collected in the trap (10). A filter (11) is attached to the pipe (6) between the dehumidifying section (9) and the detecting section (7),
The gas flowing into the detector (7) is cleaned.

However, the feature of the apparatus of this embodiment is that the combustion furnace (3) is as described above.
The collecting part (5) is directly connected to the above, and this collecting part (5) is configured as the above-mentioned reaction part. That is, a fixed amount of the collected liquid (12) is contained in the collection part (5), and the combustion product gas from the combustion furnace (3) is collected together with the carrier gas from the lower end of the collection part (5). It is configured to directly bubble the liquid. Therefore, even if the sample water injected into the combustion furnace (3) by the microsyringe (12) contains a large amount of acid and salts, and a corrosion component or an interference component in the gas detection section (7) is generated in this combustion furnace (3), These components are captured and removed by the collection liquid (12) while the combustion product gas is bubbled through the collection liquid (12) of the collection unit (5). Although water is used as the collected liquid, it is not necessary to add it from the outside because it is supplied one after another as drainage in which water contained in the combustion product gas from the combustion furnace is condensed. In general, acid and salt are often contained in sample water, but when these combustion products are dissolved in water, hydrochloric acid from chloride, nitric acid from nitrate, nitrous acid, sulfuric acid from sulfuric acid, sulfurous acid, etc. It produces a mineral acid, which makes it acidic, which serves as a reaction solution for measuring inorganic carbon as described below.

Further, the collecting section (5) also has a function as a reaction furnace for inorganic carbon as described above. That is, the collection unit (5) has an injection port (not shown) for injecting the sample, and the sample can be injected from this injection port by a microsyringe (13) or the like like a conventional reaction furnace. Is configured. In this embodiment, in order to accelerate the decomposition of dissociated carbonate ions, which are inorganic carbon, and hydrogen carbonate ions, hydrochloric acid, when injecting a sample, for example, before sample injection, or almost at the same time, or immediately after injection, nitric acid,
An acid such as phosphoric acid or sulfuric acid is also injected. An inorganic acid is used as the acid, and hydrochloric acid is particularly preferable. Usually, PH of the collected liquid
It has been confirmed that the above decomposition becomes reliable when the value is 3 or less. It is not necessary to inject this acid every time the sample is injected, and for example, if 0.5 ml of 2N-HCl is injected, the sample can be measured about 10 times. Further, as described above, when the combustion product from the combustion furnace is dissolved in the trapping liquid in the trapping portion, mineral acid is generated from the acid or salt in the sample. In most cases, even if it is not added, it has a strong acidity of PH3 or less. That is, in the present example, the acids that were conventionally discharged are effectively used.

Further, the collecting part (5) is used at room temperature and is not heated unlike the conventional case. Therefore, when measuring inorganic carbon, even if the sample contains easily oxidizable lower carboxylic acids, these lower carboxylic acids do not pyrolyze to generate carbon dioxide, and as a result, they may cause an error in measuring inorganic carbon. Therefore, the measurement accuracy can be improved.

Further, since the collecting section (5) does not heat even a sample containing salt such as sodium chloride as in the conventional case, it does not react to generate an acid vapor such as hydrochloric acid inside the sample, so that there is no error. Inorganic carbon can be measured. Furthermore, unlike the conventional method, phosphoric acid or the like is not supported on the carrier, so that a considerably larger number of samples can be injected than the conventional method.
Inorganic carbon can be accurately measured by increasing the injection amount even if the amount of inorganic carbon in the sample is very small. Therefore, although the conventional injection amount of 200μ was the limit, in the present embodiment, a sample of about 10 times or more can be used.
It has been confirmed that measurement can be performed even at a concentration of 1/10 or less (that is, the measurement sensitivity is 10 times or more).

Further, a discharge valve (5a) is attached to the collection part (5) in order to keep the collected liquid at a constant amount (see the same figure). A PH meter (5b) for controlling the PH of the collected liquid (12) can also be attached. The discharge valve (5a) is an automatic valve, and by attaching a controller thereto, excess drain can be discharged prior to measurement by a signal from the controller.

The collection part (5) is composed of a container such as glass or plastic, and a collection liquid storage part (5c) is formed in the lower part as shown in the drawing, and its diameter is in the range of 10 to 15 mm and the length is The range of 20 to 50 mm is preferable, and 1 to 10 ml of the collection liquid (1
It is good to manage the liquid level so that 2) stays at all times,
In addition, in order to prevent the scattering of bubbles generated during bubbling, the collection part (5) is provided with a spherical bubble cutting part (5d) with a diameter of 20 to 30 mm as shown in the figure to increase the cross-sectional area. It is good to leave.

In addition, when measuring organic carbon, a certain amount of trapping required for detergency is required in order to wash the combustion product gas of the combustion furnace (3) with the trapping liquid (12) of the trapping part (5). It is necessary to reserve the liquid (12). When the amount exceeds a certain amount, the discharge valve (5a) described above is opened to a constant amount. Since the standard solution is passed through the calibration solution several times in advance at the start of the measurement, the drainage from which the water in the combustion product gas generated at that time agglomerates collects in the collection part and acts as a collection solution. Sometimes, a fixed amount of the collected liquid (12) is secured.

As a sample injection means, a syringe pump can be used as an automatic injection method. In the case of this automatic injection method, the syringe pump can also be used as an acid injection means. By injecting a certain amount of acid into, the required amount of acid can be automatically injected into the collection unit (5).

Since the configuration of the apparatus of this embodiment other than the above can be configured in the same manner as the conventional apparatus, the description thereof is omitted.

Next, another embodiment of the present invention will be described. In this example, a strongly acidic ion exchange resin (H type) as a solid acid (for example, "Amberlite IR-120B") was previously collected in the collection section (5).
(Registered trademark of Rohm and Haas Company in the United States, manufactured by Organo Co., Ltd.) is featured, and the other configurations are similar to those of the above-described embodiment.

When a strongly acidic ion exchange resin is stored, it exchanges ions with cations such as hydrogen carbonate in the sample (for example, R-SO.
₃ H + NaHCO ₃ → R-SO ₃ Na + H ₂ CO ₃ ), and the product generated at this time, that is, carbonic acid, is bubbled by a carrier gas, so that it is easily converted into carbon dioxide (H ₂ CO ₃ → H ₂ O + C
O ₂ ), and the same effects as those of the above embodiment can be obtained.

As a method for accommodating the strongly acidic ion-exchange resin, for example, 2 ml of this strongly acidic ion-exchange resin is accommodated in a 50-mesh platinum wire mesh, and the accommodating solution (5) is placed in the accommodating state, and a certain amount of the collecting liquid is filled. You can leave it.

In this case, even if the reduced exchange capacity of a strongly acidic ion-exchange resin by the ion exchange reaction, easily regenerated by the type of the combustion product gas (e.g., _{R-SO 3 Na + HCl →} R-SO 3 H + Na
This ion-exchange resin can be used repeatedly because it is Cl). By storing the strongly acidic ion exchange resin in the collection part (5) in this manner,
It is not necessary to inject the acidic solution into the collection part (5) at the time of measuring the inorganic carbon, and the operation becomes simpler. Any solid acid other than a strongly acidic ion exchange resin can be used as appropriate as long as it does not hinder the above reaction.

〔The invention's effect〕

As described above, according to the present invention, it is possible to reliably and highly accurately measure inorganic carbon even if the sample contains a large amount of acid or salt, and even if the sample contains a very small amount of inorganic carbon.

Incidentally, if the solid acid is accommodated in the collection part, since the solid acid causes an ion exchange reaction, it is not necessary to inject an acidic solution into the collection part at the time of measuring inorganic carbon,
Operability is further improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the organic carbon measuring device according to the present invention. In the figure, (5) is a collection part and (12) is a collection liquid.

Claims (1)

[Claims] 1. A combustion part for injecting sample water to combust or thermally decompose organic carbon and inorganic carbon to convert all of these carbons into carbon dioxide, and injecting the sample water for reacting inorganic carbon Organic carbon measurement to measure the organic carbon from the difference between the total carbon and the inorganic carbon by calculating the total carbon and the inorganic carbon by individually detecting and quantifying each of the carbon dioxide In the apparatus, a collecting unit containing a collected liquid is connected to the combustion unit, and the combustion product gas of the combustion unit is bubbled to purify the combustion product gas. Is characterized in that the sample water inlet is provided, and the sample water is injected with the acid at the appropriate time through the inlet, and the collecting portion is configured as a reaction portion for converting inorganic carbon into carbon dioxide in an acidic aqueous solution. Measuring device for organic carbon