JP2001174447A - Method of measuring hardness and indicator for measuring hardness - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring hardness capable of measuring the hardness even of a solution having a high hardness without necessity of titrating in a two-liquid system and an indicator for measuring the hardness. SOLUTION: The method for measuring the hardness comprises steps for detecting a color developing change when the indicator for measuring the hardness is added to a solution to be measured, and changing the adding amount of a desensitizer in the indicator based on the detected value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hardness measuring method for measuring hardness of industrial water, domestic water and the like, and a hardness measuring indicator.

[0002]

2. Description of the Related Art As is well known, a water supply line for cooling equipment such as a boiler, a water heater, or a cooler is required to prevent scale adhesion in the cooling equipment, so that the hardness of the water contained in the supply water is reduced. An automatic regeneration type water softener (hereinafter, abbreviated as “water softener”) of a type that removes hardness using an ion exchange resin is widely used.

[0003] Conventionally, the hardness of supply water (generally, the hardness is often high) before passing through a water softener has been measured as follows.
There is a method of titrating with EDTA (ethylenediaminetetraacetic acid) using a metal indicator {calmagite, EBT (eriochrome black T) or the like} which changes color by reacting with hardness (Ca, Mg, etc.) in an alkaline atmosphere. However, in this method, the measurement is troublesome because the titration is performed in a two-part system. Therefore, it is required that the hardness measurement be performed in a one-component system without titration with EDTA.

Further, the conventional method using an indicator for detecting hardness leakage is effective for detecting the hardness of supply water after passing through a water softener. However, the hardness of the supply water before passing through the water softener cannot be used because the range of hardness to be measured is too wide. Therefore, there is a need for an indicator that can measure even supply water having high hardness.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a hardness measuring method and a hardness measuring indicator which do not require titration in a two-part system and can measure even supply water having high hardness. It is intended to be.

[0006]

Means for Solving the Problems The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is directed to a method for measuring a change in color when a hardness measurement indicator is added to a solution to be measured. It is characterized in that the mixing ratio of the desensitizer in the hardness measurement indicator is changed based on the detected value.

According to a second aspect of the present invention, a change in color development when an indicator for hardness measurement is added to a solution to be measured is detected, and the addition amount of the indicator for hardness measurement is changed based on the detected value. Features.

Further, the invention according to claim 3 is characterized in that the hardness measuring indicator comprises at least a metal indicator and a desensitizer.

[0009]

Next, an embodiment of the present invention will be described. INDUSTRIAL APPLICABILITY The present invention can be suitably implemented in a water supply line to a solution to be measured, for example, a boiler, for measuring hardness of supply water before passing through a water softener. As a method of measuring the hardness in the present invention, the amount of a desensitizer (an agent that forms a complex ion with some metal ions of the hardness component in water and reduces metal ions that react with the metal indicator) is added. Is changed. The desensitizer exhibits a reaction similar to that of the metal indicator, but needs to have a reactivity that does not form a complex ion with all metal ions. The use of a desensitizer results in a measurement similar to that in the case of a low value of hardness without a desensitizer. That is, accurate measurement is possible even with a high hardness solution to be measured. As the desensitizer of the indicator for measuring hardness in the present invention, polyacrylate, iminodiacetic acid, citrate and the like are applied.

Another advantage of using the metal indicator is that the metal indicator is a kind of chelating agent, and forms complex ions with metal ions such as magnesium ion and calcium ion, which are the main components of hardness, and develops color more sharply. Therefore, it is suitable for hardness measurement. As the metal indicator in the present invention, a metal indicator containing a dye represented by any one of formulas I to III and the like are applied.

[0011]

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[0012]

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[0013]

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In the indicator for measuring hardness according to the present invention, a surfactant or a sensitizer is used in order to improve the cleaning performance of the measuring section of the hardness measuring device and to eliminate the difference in the coloring properties of magnesium ions and calcium ions. An agent (agent having an effect of increasing the detection sensitivity) can also be added.

Further, as a measuring method, a predetermined amount of the solution to be measured is introduced into a transparent container, an indicator for hardness measurement is poured into the transparent container and mixed, and the solution to be measured near a specific wavelength is detected by a detecting means. Is determined.

As described above, a more accurate hardness can be measured by making use of the performance of the desensitizer and changing the amount of the desensitizer added according to the hardness. Also, a method of changing the amount of the hardness measurement indicator to be added depending on the hardness can measure the hardness more accurately. Further, when these methods are used, the reaction can be performed in a one-component system.

[0017]

Next, specific embodiments of the present invention will be described in detail. As a hardness measuring method in the present invention,
It is characterized in that an indicator for hardness measurement containing a desensitizer is used. Therefore, the desensitizer will be described first.
The desensitizer here has the same chelating effect as the metal indicator. However, the difference from the metal indicator is that the metal indicator forms complex ions with the metal ions of all the hardness components, but the desensitizer forms complex ions with some of the metal ions of the hardness component. is there. Thereby, the number of metal ions in the solution to be measured is reduced, and the measurement becomes the same as the measurement of the solution to be measured having a low hardness, and the measurement of the solution to be measured having a high hardness becomes possible. That is, as the desensitizer in the present invention, polyacrylate, iminodiacetic acid, citrate and the like are suitable.

Next, the metal indicator will be described. As a method for selecting the metal indicator, it is important to first develop a color for the hardness component. In addition, the presence of a maximum value of absorption at a specific absorption wavelength in the color development is one of the conditions to be selected as a metal indicator. Furthermore, it is also important that the metal indicator has a certain degree of solubility and does not deteriorate its performance when converted into an aqueous solution. That is, as a metal indicator satisfying the above conditions, carmagite represented by the general formula I and the like are preferable.

[0019]

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Further, EBT, Eriochrome Blue Black B and the like represented by the general formula II are preferred.

[0021]

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Further, NN indicators represented by the general formula III, hydroxynaphthol blue, chalcone, and the like are suitable as the metal indicators.

[0023]

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Next, the present invention will be described in more detail. The inventors of the present invention added 99.5% by weight of an organic solvent to which 0.5% by weight of a metal indicator (calmagite) was added (FIG. 1).
89.5% by weight of an organic solvent to which 0.5% by weight of a metal indicator (calmagite) and 10% by weight of a desensitizer (sodium polyacrylate) were added (FIG. 2);
4.5% by weight of metal indicator (calmagite) 0.5% by weight and desensitizer (polyacrylic acid sodium salt) 15% by weight
(FIG. 3), and 0.5% by weight of a metal indicator (calmagite) and 20% by weight of a desensitizer (polyacrylic acid sodium salt) in 79.5% by weight of an organic solvent (FIG. 4). The experiment was performed using. Here, an experiment was performed using ethylene glycol and triethanolamine as organic solvents.

The results are shown in FIGS. Fig. 1 shows 50pp because no desensitizer was added to the hardness measurement indicator.
It is not possible to measure the density with a hardness of m or more. Also,
2 to 4 show changes in the blending ratio of the desensitizer in the hardness measurement indicator. By increasing the blending ratio of the desensitizer, the difference in transmittance between high hardness (50 ppm or more) is reduced. Increase and decrease the difference in transmittance for low hardness (50 ppm or less). That is, when the blending ratio of the sodium polyacrylate is increased, the resolution of the high hardness increases, and the resolution of the low hardness decreases. Therefore, when the compounding ratio of the desensitizer is increased, a higher hardness concentration can be accurately determined. Conversely, it can be seen that, for the measurement of the solution to be measured having a low hardness, it is better to use a smaller amount of the desensitizer. Therefore, changing the amount of the desensitizer in the hardness measurement indicator can increase the accuracy of the hardness concentration measurement.

Next, an increase in the amount of the hardness measurement indicator will be described with reference to FIG. FIG. 5 shows the results when the addition amount of the hardness measurement indicator was changed.
The amount of the indicator for hardness measurement was set to 0.30%, 0.60%, to the volume in the transparent container (not shown) of the hardness measurement device.
An experiment was performed using the values changed to 0.90% and 1.20%. As is clear from FIG. 5, even if the amount of the hardness measurement indicator is increased, the same effect can be obtained because the amount of the added desensitizer increases. Therefore, by increasing the amount of the hardness measurement indicator to be added, a higher hardness concentration can be accurately determined.

Here, the inventors conducted experiments on the above-mentioned EBT and other metal indicators in the same manner as in the above-mentioned karmagite. The results also confirmed that the results were almost the same as those of the above-mentioned karmagite.

The inventors conducted experiments on other desensitizers such as disodium iminodiacetate in the same manner as in the above-mentioned sodium polyacrylate. It was also confirmed that the results were almost the same as those of the sodium polyacrylate.

Further, the inventors clean the measuring section of the hardness measuring apparatus by blending a surfactant or a sensitizer (a drug having an effect of increasing the detection sensitivity) with the hardness measuring indicator. It was confirmed that the washing performance at the time was improved, and that the difference in color development between magnesium ions and calcium ions could be eliminated.

[0030]

As described above, according to the present invention, there is provided a hardness measuring method and a hardness measuring indicator which do not require titration in a two-part system and can measure even a solution to be measured having a higher hardness. Can be. Furthermore, if measurement at a high concentration becomes possible, the exchange time can be accurately determined from the exchange capacity of the water softener (the exchange capacity of the ion exchange resin used in the water softener), and the regeneration timing Can be accurately determined.

[Brief description of the drawings]

FIG. 1 is a graph showing the results when a hardness measurement indicator containing no sodium polyacrylate is used.

FIG. 2 shows a mixing ratio of sodium polyacrylate of 10
It is a graph showing the result at the time of%.

FIG. 3 shows a blending ratio of sodium polyacrylate of 15
It is a graph showing the result at the time of%.

FIG. 4 shows a blending ratio of sodium polyacrylate of 20
It is a graph showing the result at the time of%.

FIG. 5 is a graph showing the results when the addition amount of an indicator for hardness measurement was changed.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takanari Kume 7, Horie-cho, Matsuyama-shi, Ehime Miura Industrial Co., Ltd. (72) Inventor Isamu Yoneka 7, Horie-cho, Matsuyama-shi, Ehime Miura Industrial Co., Ltd. F-term (Reference) 2G042 AA01 BC02 CA02 CB03 DA08 FA11 FA14 FB02

Claims (3)

[Claims] 1. The method according to claim 1, wherein a change in color development when an indicator for hardness measurement is added to the solution to be measured is detected, and the amount of the desensitizer in the indicator for hardness measurement is changed based on the detected value. Hardness measurement method. 2. A hardness measurement method comprising: detecting a change in color development when a hardness measurement indicator is added to a solution to be measured; and changing the addition amount of the hardness measurement indicator based on the detected value. 3. The hardness measurement indicator according to claim 1, wherein the hardness measurement indicator comprises at least a metal indicator and a desensitizer.