JPH01262462A - Method of measuring concentration of liquid and automatic concentration measuring instrument and automatic concentration control device using said method - Google Patents

Abstract

PURPOSE:To improve durability by preparing a specified volume of a liquid to be inspected and known reagent such as acid or alkali of the equiv. to the standard value preset with the liquid to be inspected, introducing these liquids into a reaction measuring instrument, mixing and stirring the liquids and measuring the signal emitted by an indicating electrode. CONSTITUTION:The title instrument consisting of a liquid to be inspected tank 1, a known reagent storage tank 4 in which the known reagent 5 is stored, a reaction measuring cell 7, and a control box 11, etc., is built to, for example, a process line device. The indicating electrode 10 consisting of a pH electrode is provided in the cell 7 and is connected to a box 11. After the reagent is collected into the cell 7, the specified volume of the liquid to be inspected is introduced into the cell 7 where the liquids are stirred and mixed. The pH value thereof is then measured and the box 11 displays the signal from the electrode 10 on a display device 11a. The control box compares the signal with the reference value at the equiv. point of the liquid to be inspected and the known reagent, computes the concn. of the liquid to be inspected and transmits the control output to control valves 12, 12. The electrode 10 is, therefore, used over a long period of time.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a method for measuring the concentration of a liquid such as an acid or alkaline solution using an indicator electrode, and an automatic concentration measuring device i' using the method; Regarding a control device.

[Prior art] Conventionally, as a method for measuring the concentration of liquids such as acids and alkaline solutions using an indicator electrode, the test liquid exclusively for acids and alkalis, or a diluted version of the test liquid itself, is used with an I'l+ electrode or an ORI electrode.
'An indicator electrode such as an immersed or constant electrode;
1) A method is known in which a test liquid is collected and a reagent that reacts with the test liquid is titrated to perform Pl+ titration, conductivity titration, redox titration, amperometric titration, or photometric titration.

Devices that automatically perform these measurements and devices that automatically control the concentration of the test liquid based on the measurement results are also known.

[Problems to be Solved by the Invention] In this conventional method, when the test liquid is acidic or alkaline, for example, the electrode itself wears out quickly and cannot withstand long-term use. There was a problem that accurate measurement could not be performed due to i difference.

[1] The first aspect of this invention is that, although basically relying on the conventional method using an indicator electrode, the concentration of an acid or alkaline liquid can be measured repeatedly over a long period of time with a single indicator electrode;
In this case, it is an object of the present invention to provide a measuring method with higher measurement accuracy than conventional methods, as well as an automatic concentration measuring device and an automatic concentration controlling device using the method.

[Means for Solving the Problems] - In order to achieve the above-mentioned technical problems, this invention prepares a constant test liquid, and also prepares a set label of this test liquid, including F. A known reagent, such as an acid or alkali, is added to the value, and the known reagent and the liquid to be aspirated are mixed and stirred, and then the signal emitted by the indicator electrode in this mixed liquid is measured. It is something.

This invention also provides an automatic concentration measuring device n for liquids such as acids and alkaline liquids with a test liquid tank and a constant concentration from the test liquid tank;
11. A meter for measuring tt of L test liquid, a reagent tank, and a stage for collecting a known reagent at a constant i2t from the reagent tank;
; 1. A reaction measurement tank for mixing and stirring the test liquid and the reagent;
The system includes an indicator electrode attached to the reaction measurement tank, display means for displaying signals sent from the indicator electrode, and a control box that automatically controls these measurement systems.

This invention further provides an automatic concentration control device n for liquids such as acids and alkaline liquids, which is connected to a test liquid tank and intermittently supplies three test liquids of 11[deg.] to the test liquid tank: ), a reagent tank, a means for collecting the known reagent intermittently from this reagent tank; A control box that compares and calculates an indicator electrode attached to the indicator electrode and a signal sent from this indicator electrode, and a control box that compares and calculates the signal sent from the indicator electrode, and the control box that
It is configured to include a flow rate control valve for replenishing liquid for the sample liquid described in i.

[Effect] The pH value, ORP value, etc. indicated by the indicator electrode shows a rapid change at the point of 1:5-+1L of the test solution and reagent, so based on this,
1i, and the concentration of the test liquid can be measured based on whether the pH value or ORP value is higher or lower than this value.

Furthermore, the measurement system is automatically controlled by the control box, and batch-type concentration measurements of the sample liquid can be repeatedly performed with extremely high accuracy.

Furthermore, the control box automatically controls the flow control valve for the replenisher to the test solution, allowing the concentration of the test solution to be controlled intermittently and continuously with extremely high precision. be.

[Example] Hereinafter, the present invention will be explained in detail based on the drawings. A Pl+ electrode is used as an indicator electrode, and this I'l+ electrode is connected to a reaction measurement tank containing a test solution consisting of hydrochloric acid of a constant fit + 1 CI. When titration measurements were performed using a known reagent of caustic soda N, 011, as shown in Figure 1,
A rapid change in pH value appeared near the Fit point (neutralization point) P117, and a large change in the indicated value was obtained with respect to the concentration change after +iii.

In addition, using the ORI'' electrode as the indicator electrode, titration of iron sulfate F, SO, with small potassium chromate x2crxL was performed as described above, and as shown in Figure 2, the i1 point was A sudden change in potential occurred near 480 mV, and a large change in the indicated value was obtained with respect to the change in concentration after 11:i.

Therefore, when the P11 electrode is used as an indicator electrode,
Control setting value of gate 17 is J! lv! When using an ORP electrode, applying 480 mV once to the setting base will result in a large change in the indicated value for a small change in concentration, making it possible to measure the concentration of extremely high test liquids of 111 degrees. I found out what I can do.

At the same time, since the indicator electrode will not be corroded at this point, a certain amount of the test liquid is put into a reaction measurement tank equipped with an indicator electrode, and a prefit (this test liquid and the By adding the 11 known test solutions, stirring and mixing both solutions, and applying the above-mentioned control settings to J^ and using the patch method, the concentration can be measured in a short period of time. It was found that the indicator electrode also lasts a long time without being corroded.

Next, FIG. 20 requires manufacturing control of the liquid used in this invention. The case is shown in which it is implemented by incorporating it into a simple six-type process line equipment, where 1 is a test liquid tank in which a test liquid 1d of an acid or alkali liquid cap whose concentration is to be measured is stored; Reference numeral 2 denotes a device to be tested, 3 is a pump, and this pump 3 sends the test liquid 1a from the test liquid tank 1 to a total of 1 devices 2. Liquid 1a,
The liquid is stored in the Nido 11 tube Za. 4 is a known reagent storage tank storing a known reagent 5 such as an acid or alkaline solution, 6 is a pump, and 7 is a reaction measurement tank. ' )The value? A known reagent 5 having a constant ri required for neutralization, for example, to be transferred to a one-quantity point, is intermittently led from a known quantity mulberry storage tank 4 to a reaction measurement tank 7 and stored therein. The test liquid 1a is added to this reaction measurement tank 7! 11 pipe 2+11 via a switching valve 8. Reference numeral 9 denotes a stirrer, which may be stirred not by a motor as shown in the drawing but by magnetic force or other known means. 10 is an indicator electrode consisting of a pH electrode, for example, and this indicator electrode may also include a QRT' electrode,
- It may be replaced with an ion electrode, an oxygen electrode, a conductivity electrode, a photometric (colorimetric) electrode, etc. Reference numeral 11 is a control box, and a display section 11a displays the signal from the indicator electrode 10.
11" signal is taken as a potential difference, and 1 is set to the base at the rI point of the test liquid and known reagent! 111 to calculate the concentration of the test liquid and apply the control 111 force to the control valve 1.
2. Tell 12 about the refill fluid! +1 is controlled. In addition, 13 is an air pump, and 15 is a three-way switching valve, which is operated by a motor 16 to discharge the mixed liquid in the first reaction measurement tank 7, wash the inside, and then drain the washing water. It is something.

Next, an example in which this apparatus was used to control the alkali concentration in an electroless steel plating solution will be further explained with reference to FIG.

The reaction measurement tank 7 was equipped with an r/damage gate 1 electrode (a glass membrane composite l pickle 10).
Sulfuric acid, a known reagent required for 1. lN-11,
A constant 1 liter (approximately 5 ml) of soybean solution was collected from the known reagent storage tank 4 into the reaction measurement tank 7 via the pump (3).

Next, a constant Fit (approx. 10 mj2
) through pump 3;, 12? The mixture was introduced into the reaction measuring tank 7 through the two-way switching valve 8 of J2, stirred and mixed using the stirrer 9, and the reading was quickly stabilized to measure the 1) 11 value.

If the plating liquid is similar to the standard I'll value, the display r' stage 11a shows neutral (PI+71), but is the plating liquid the standard I'll value?
If there was a difference in concentration from %'PI+(BI), the pH change of the mixed solution in the reaction measurement tank 7 was displayed as shown below.

, if the plating liquid was lower than the standard 1111 value during the trial run, 1) the 11 value indicates acidity (lower than 1'117);
Conversely, if the value is higher than the standard 1'll value, it becomes alkaline (
However, at the stage of actual operation, copper in the sulfuric acid barrel was...! Because it is oxidized and the sulfate group remains,
and'ff1L, but always/I! 2('1 direction, and the number 471 was sent to the control box 11. The control box 11 calculates based on the setting h^P117, and sends the control output to the control box p+z, 12. Activate the control valve 12.1z, replenish the replenisher, and set the concentration of the plating liquid (1°). As a result, by using this method and device, the Pl + setting value of the plating liquid can be set to 1°.
It was found that continuous operation was possible while controlling the pH to within 2.5±0.1, which was much more accurate than the conventional pH value of approximately +2.5±0.1.

The following embodiments have all been described in the case where the test liquid is alkaline, but they can be carried out in the same way even when the test liquid is acid by sparing the alkali.

Further, although the first embodiment is for acid-base titration, it goes without saying that the titration method described in section 3 above, such as oxidation and reduction titration, can be carried out in the same manner.

[Effects] Since the present invention is configured as described above, the following effects can be achieved.

By configuring as claimed in claim 1, the concentration can be measured using the rat point as a cow. This makes it possible to perform highly accurate measurements under stable conditions.

By configuring as claimed in claim 2, the concentration of the test liquid can be automatically and repeatedly measured with accurate accuracy.

By configuring as set forth in claim 3, the concentration of the test liquid can be automatically controlled with an unprecedentedly accurate FI77.

[Brief explanation of the drawing]

Figure 1 is a titration curve diagram using a pH electrode, Figure 2 is an ORI titration curve diagram.
Figure 3 is a block diagram of an apparatus for carrying out this invention. I... Test liquid tank 2... Automatic meter M device 4 3... Pump 4... Mulberry storage tank 6... Pump 7... Reaction measurement tank 8... Switching valve 9 ... Stirrer 10 ... Indicator electrode 11 ... Control box 11a ... Display 1 stage 12 ... Control valve Fig. 1 Fig. 2

Claims (1)

[Claims] 1. Reaction measurement using an indicator electrode, in which a certain amount of a test solution is prepared, and a known reagent such as an acid or alkali is added in an amount equivalent to a standard value set in advance for the test solution. After introducing the test liquid into a reaction measurement tank and stirring it with the known reagent, the concentration of the test liquid is measured based on the signal output from the indicator electrode in this mixed liquid. A method for measuring the concentration of a liquid, characterized by: 2. A test liquid tank such as acid or alkaline liquid, a measuring device that intermittently measures a fixed amount of test liquid from this test liquid tank, and a reagent tank, which measures a fixed amount of test liquid intermittently from this reagent tank. a means for collecting a known reagent, a reaction measurement tank for mixing and stirring the test liquid and the reagent, and an indicator electrode attached to the reaction measurement tank;
An automatic concentration measuring device characterized by comprising a display means for displaying the signal sent from the indicator electrode, and a control box for automatically controlling these measurement systems. 3. A test liquid tank such as acid or alkaline liquid, a measuring device that intermittently measures a fixed amount of test liquid from this test liquid tank, and a reagent tank, which measures a fixed amount of test liquid intermittently from this reagent tank. a means for collecting a known reagent, a reaction measurement tank for mixing and stirring the test liquid and the reagent, and an indicator electrode attached to the reaction measurement tank;
An automatic concentration control device comprising: a control box that compares and calculates signals sent from the indicator electrode; and a flow rate control valve for replenishing the liquid to be aspirated, which is controlled by the control box.