JPH03180749A - Continuously measuring instrument for concentration of dissolved oxygen in high-temperature water or high-temperature aqueous solution - Google Patents

Abstract

PURPOSE:To allow a stable, automatic and continuous analysis with small long-time errors by installing a bubble separating and removing part just before the flow system of the electrode cell of a dissolved oxygen meter. CONSTITUTION:A structural part 1 of branch pipes is provided just before the flow system of the electrode cell 2 of the dissolved oxygen meter and one system after the branching is connected between through a pump 3, a cooler 5 and a cell 2 to a conduit 16. The other system is connected through a pump 4 to a conduit 16 and respective sample liquids 17 are returned to a sample tank 18. The bubbles surely flow into the pump 4 system if the liquid flow rate ratio on a pump 4 side with respect to a pump 3 side is specified to 1 to 2. The sample liquid to be measured is eventually admitted into the cell 2 and is analyzed after the bubbles are separated and removed in the initial stage before stirring. The continuous measurement is thus executed stably with the small measurement errors in the high-temp. water and the high-temp. aq. soln.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is an apparatus for continuously measuring dissolved oxygen concentration in high-temperature water or high-temperature aqueous solution, and particularly for measuring dissolved oxygen concentration in plating solutions such as electroless copper plating used at high temperatures. Concerning a continuous measurement device.

(Prior Art) The dissolved oxygen concentration in the high-temperature plating solution is one of the important conditions as well as the components of the plating solution, and how well it is controlled greatly affects the quality of the plated product.

Therefore, it is important to accurately measure and control the dissolved oxygen concentration in the high temperature plating solution during plating operation.

By the way, the measurement temperature range of currently commercially available diaphragm-type dissolved oxygen meters is limited by the temperature compensation range based on temperature changes in the oxygen permeability characteristics of the diaphragm and the heat resistance of the sensor electrode, and is usually 5. -40°C, and is often measured at 20-30°C, where there is little temperature change during measurement.

Therefore, in an electroless copper plating solution operated at 70 to 80°C, it is impossible to directly use a diaphragm electrode type dissolved oxygen meter.

As a prior art technique that has solved the above-mentioned problems, there is a Japanese Patent Application No. 141985/1985 filed by the present inventor entitled ``Method for Measuring Dissolved Oxygen Concentration in High-Temperature Water or High-Temperature Aqueous Solution''. This method involved a batch-type measurement in which the sample to be measured, high-temperature water or high-temperature aqueous solution, was placed in a container, cooled with air cut off, and then measured using a diaphragm-type dissolved oxygen meter.

(Problem to be Solved by the Invention) However, the above method can obtain an accurate dissolved oxygen concentration in highly mixed water or high-temperature aqueous solution relatively easily and in a short time, and is fully applicable to plating solutions that operate at high temperatures. However, this method has the problem of manual analysis and batch-type measurement, and there is a problem that automation and continuous analysis are necessary, especially in plating manufacturing sites.

Therefore, in order to solve the above problem, when sample liquid to be measured is continuously collected from a plating tank etc. through a conduit, air bubbles (air) flow into the conduit along with the sample liquid, and these bubbles move inside the conduit and enter the pump. The concentration of dissolved oxygen in the sample solution increases when the sample solution is stirred with the sample solution, and if the above-mentioned continuous sampling is performed for a long time and the above-mentioned air bubbles flow into the electrode cell of the diaphragm-type dissolved oxygen meter, the cell There was a problem in that the analytical readings of the oxygen meter became extremely unstable due to agitation within the tank and the adhesion of air bubbles to the surface of the diaphragm.

The above-mentioned cause of bubble inflow is mainly due to aeration performed in plating tanks, etc., but there are also other causes, such as when the liquid inside the tank is higher than the outside temperature (room temperature) and the liquid inside the tank is hotter than the outside temperature (room temperature). This is due to the fact that it is not stationary during work, and therefore contains more air than in the gas-liquid equilibrium state at each temperature.

That is, in plating waves that are at high temperatures and are undergoing aeration, the gas-liquid state does not reach equilibrium to a greater or lesser extent. Therefore, when analyzing dissolved oxygen in a liquid in the state described above, it is necessary to obtain a precise and absolute measurement value such as the air-saturated dissolved oxygen concentration, which holds true for a liquid that has been allowed to stand still for a sufficient period of time to reach equilibrium. This is impossible no matter what method is used, and from the standpoint of production technology, it is necessary to achieve the original objective by automatically and continuously obtaining relative values with high reliability and small errors. be.

The present invention solves the above problems and provides an apparatus that can stably measure dissolved oxygen concentration in high-temperature water or high-temperature aqueous solution with little error over a long period of time, and can perform automatic and continuous analysis. It is.

(Means for Solving the Problems) The present invention allows for long-term analysis by separating and removing air bubbles that have flowed into the conduit before being stirred by a pump or the like before the flow system of the dissolved oxygen meter electrode cell. This device was developed based on the knowledge that stable analysis values with small errors can be obtained, and the device is a continuous measuring device for dissolved oxygen concentration in high-temperature water or high-temperature aqueous solution, with a bubble separation and removal section installed before the flow system of the dissolved oxygen meter electrode cell. It is.

The means for separating and removing the bubbles is to connect a branch pipe structure upstream of the dissolved oxygen meter electrode cell in the flow system.

The present invention will be described below with reference to FIG. 1, which shows a typical device configuration of the present invention.

A branch pipe structure 1 is provided in front of the dissolved oxygen meter electrode cell 2 in the flow system, and a pump 3. A pump 4 is provided, and one pump 3 is followed by a cooling part 5, and further thereafter a dissolved oxygen meter electrode cell 2.
A conduit 16 connects the above parts, pumps, etc. After the dissolved oxygen meter electrode 2, the sample liquid 17 is returned to the sample liquid tank 18 through the conduit 16, and nothing is provided after the pump 4, which is the other system, and the sample liquid 17 is returned to the sample liquid tank 18 through the conduit 16. Return to Note that the pump 3 may be provided after the cooling section 5 or after the dissolved oxygen meter electrode cell 2.

Above pump 3. When the system of the pump 4 is called the cell side and the bubble inflow side, respectively, the liquid flow rate ratio of the pumps 3 and 4 is preferably 1 or more, and more preferably 1 or more and 2 or less, as a ratio of the bubble inflow side to the cell side. .

If the liquid flow rate ratio is 1 or more, bubbles will more reliably flow into the bubble inflow side. In addition, analysis is possible even if the above liquid flow rate ratio is 2 or more, but in reality there is a limit to the amount of liquid that can be delivered by the pump, and it is preferable that the sample liquid in cell 2 be replaced more quickly. It is not preferable to lower the flow rate of the pump 3 on the cell side as the liquid flow rate ratio becomes 2 or more.

The branch pipe structure 1 is not particularly limited in material, shape, etc. as long as it is branched, but it is preferably transparent so that the internal condition can be monitored, and it is a T-shaped or Y-shaped transparent plastic tube that is easy to obtain if you keep it. Connectors are good. The branch pipe structure 1 is preferably installed so that the direction of movement of the two pipes after branching is upward with respect to the horizontal plane on the bubble inflow side, and downward with respect to the horizontal plane on the cell side, By using the above-mentioned direction of the pipe and the above-mentioned pump inflow ratio, the bubbles can be reliably separated and removed by the buoyancy and flow rate of the bubbles themselves.

The conduit 16 is not limited in quality, shape, etc., but it is preferably transparent so that the internal situation can be monitored, such as a silicone rubber tube or fluorine rubber tube that is transparent, easy to handle, and has chemical resistance. Tubes are good. The conduit 16 extending from the sample collection section 6 to the branch tube structure section 1 can be kept warm by using a heat insulating tube 7.

The sample collection section 6 does not require any special structure, but if the amount of air for aeration is large, a fine cloth or a glass pole filter can be attached.

The cooling unit 5 may be constructed by simply passing the conduit 16 through running water, but it may also be constructed using a transparent Teflon coil tube or the like and a cooling constant temperature bath 9.
It is better to use

As the pumps 3 and 4, tube pumps, bellows pumps, magnet pumps, and other types of scales can be used, but tube pumps or the like are preferable because they can easily control the liquid flow.

The dissolved oxygen meter electrode cell 2 is not particularly limited in material, but is preferably made of a transparent material, such as transparent acrylic, and has a structure in which the inside of the cell is filled with sample liquid and sealed from the outside air by a shield 10. Good. It is also preferable to insert a stirrer chip 11 into the bottom of the cell and stir the sample liquid inside the cell using a magnetic cooler 12 at the bottom of the cell.

The diaphragm type dissolved oxygen meter 14 may be of a galvanic cell type or a polaro electrode type. Further, a recorder 15 can be connected to the diaphragm type dissolved oxygen meter 14.

(Function) The present invention separates and removes air bubbles flowing into the conduit at an early stage before they are stirred, cools them, and then flows the 1ii11J constant sample solution into the dissolved oxygen meter electrode cell for analysis. , the influence of air is small, and the measurement error of dissolved oxygen concentration in high-temperature water or high-temperature aqueous solution is small, allowing stable and continuous measurement.

(Explanation of Examples) Hereinafter, the present invention will be explained by examples.

FIG. 2 shows the results of continuous measurement of dissolved oxygen concentration for about 100 hours using the apparatus and conditions shown below for a thick electroless copper plating solution that was continuously operated with the composition and conditions shown below.

(Sample solution) (Sample solution composition per 12) CuSO40.03-0.04 mol EDTA O, 08-0.10 mol PH (N
aOH) 12.3±0.1 (25℃)HCHO
0.04-0.05 mol polyethylene glycols, 0-2. Ogα, α′−
Dipyridyl 25-30mg Pure water Amount to bring the total amount to 1℃ (sample liquid operating conditions) Liquid temperature Near 0±1℃ Aeration: Approx. 200ml/min・l liquid circulation
: Plated area: 2dbo/l Replenisher: CuSO4, NaOH.

HCHO (Continuous AT main equipment/conditions) (Main parts of the equipment) Branch pipe structure two T-type tube connectors; made of transparent polymethylpentene resin, ■Benuchi Seieido pump: Peristaltic pump (tube pump) manufactured by AT-■ 5J-1215 type conduit: silicone rubber tube; inner diameter 3III
Dissolved oxygen meter: Galvanic battery type, Do manufactured by Toa Denpa Kogyo ■
-25A type cooling constant temperature bath: ■ Cynics LC-102 type (equipment/
Analysis conditions) Measurement time: Continuous approximately 100 hours Pump flow rate: Cell side 10 m1/min.

Air bubble inflow side 12m1/min Stirrer stirring in the cell: Yes Dissolved oxygen meter calibration: 25℃ saturated water once Cooling water temperature: 25℃ (constant) Sample liquid temperature in the cell: 30±2℃ Sample collection section filter: Yes (made of cloth) Sample collection location: Approximately 50 cm below the liquid level From these results, the dissolved oxygen concentration over 100 hours was 3.2 to 4.
lppm, and these values are approximately 4, calculated from literature values for air saturated dissolved oxygen concentration at 70°C (Chemical Handbook Basic Edition ■1, edited by the Chemical Society of Japan, published by Maruzen Co., Ltd., June 20, 1975). There is no difference compared to .0ppm, so
It can be seen that by using the apparatus of the present invention, continuous measurement can be performed stably and with small errors over a long period of 100 hours. In addition,
The reason why the dissolved oxygen concentration decreases over time in the above results is thought to be due to changes in the cross section and plating rate, and the reason why the concentration goes up and down in a relatively short period of time is due to the change in the plating rate. This shows the influence of the inflow and outflow of substances (products), and conversely, it can be seen that by using the apparatus of the present invention, it is possible to analyze subtle changes in concentration as shown in -1-.

(Four Effects) As explained in Section 2 below, the apparatus of the present invention provides the following effects.

(1) The high-temperature aqueous solution to be measured (l) is cooled to a temperature below the usable temperature of the dissolved oxygen meter at the time of measurement, so the electrode will not be damaged.

(2) Since bubble separation and removal is performed before the dissolved oxygen meter electrode cell, stable dissolved oxygen concentration values with small errors can be obtained.
It can be obtained continuously for a long time of about 00 hours.

(3) Since the analysis is automatic and continuous, it is easy to set up the device once, and it is easy to manage the concentration of dissolved oxygen in high-temperature plating acids such as thick electroless copper plating.
Improves the quality of plated products.

(4) The parts that make up the device are not special and are easily available, and the device as a whole is relatively simple, making adjustment and maintenance easy.

[Brief explanation of drawings]

FIG. 1 is an overall system diagram showing an overview of a continuous measuring device according to the present invention, and FIG. 2 is a characteristic diagram showing continuous measurement results of an embodiment according to the present invention. 1... Branch pipe structure section (bubble separation/removal section) 2... Dissolved oxygen meter electrode cell 3... Pump (cell side) 4... Pump (bubble inflow side) 5... Cooling section 6 ... Sample l night collection section 7 ... Insulating material 8 ... Air lane 9 ... Cold Jilt constant temperature bath 10 ... Nold 11 ... Stirrer chip 12 ... Magnetic stirrer 13 ... Dissolved Oxygen meter electrode 14...Dissolved oxygen meter body 15...Record word 1 16...Conduit 17...High temperature sample liquid 18...Sample liquid sentinel

Claims (1)

[Claims] 1. In the sample liquid flow system, a bubble separation/removal section is provided before the dissolved oxygen meter electrode cell, and the device configuration includes a sample collection section, the bubble separation/removal section, a cooling section, and a pump. , a continuous measuring device for dissolved oxygen concentration in high-temperature water or a high-temperature aqueous solution, comprising the dissolved oxygen meter electrode cell, the diaphragm-type dissolved oxygen meter, and a conduit connecting each of the above parts. 2. In claim 1, the bubble separation/removal section has a branched pipe structure, and after a pump is connected to each of the two conduits connected to the branched pipe, a dissolved oxygen meter is installed only in one of the two pumps. The electrode cells are connected by a conduit, and the liquid flow rate ratio of the two pumps is a ratio of the liquid flow rate of the other side to the liquid flow rate of the cell side, and is 1 or more, and more preferably 1 or more and 2 or less. Continuous measuring device for dissolved oxygen concentration in high-temperature water or high-temperature aqueous solution.