KR20060044816A - Hardness measurement reagent - Google Patents

Abstract

The present invention is intended to realize a reagent for measuring hardness, in which the number of measured subjects becomes sensitively discolored near the management hardness.

The hardness measurement reagent of the present invention contains an alkali metal salt of a dye, triethanolamine, a glycol compound, and a chelating agent selected from eryochrome black tee or calmagite.

Hardness Reagent, Hard Water Softening, Eriochrome Black Tie, Triethanolamine, Chelating Agent

Description

Hardness measurement reagent

The present invention relates to a hardness measurement reagent used for measuring the hardness contained in industrial water, domestic water and the like.

As is well known, hardness components (Ca ²⁺ and Mg) contained in raw water, such as industrial water or domestic water, are used in water supply lines for cooling equipment such as boilers, water heaters, or coolers, in order to prevent scale attachment in the cooling equipment. ²⁺ ) is connected to the water supply line.For example, connect the hard water softening device using ion exchange resin to the water supply line and replace the hardness components (Ca ²⁺ and Mg ²⁺ ) in the raw water with Na ⁺ . In addition, the obtained softened water is supplied to the cold heat equipment as a water supply.

In the case of using the water softening device, if the ion exchange resin contained inside the device deteriorates or the regeneration of the ion exchange resin is not sufficient, it is insufficient to replace the hardness component in the water supply with Na ⁺ . . Therefore, it is necessary to set the hardness allowed in advance according to the hardness of raw water in the area or place where the cold heat equipment is installed, and to periodically measure the hardness in the water supply passing through the hard water softening device. If the hardness in the water supply exceeds the upper limit of the allowable value (hereinafter referred to as 'management hardness'), it is determined that the hardness is leaking, so that the water supply maintains the predetermined hardness range by exchanging or regenerating the ion exchange resin. Is processed.

As a method for determining the hardness in the water supply, for example, the water to be measured obtained from a water supply is a non-aqueous hardness measurement reagent containing Eriochrome Black T (hereinafter referred to as EBT) as a pigment. In addition to this, a method of using the color of the water under measurement as an index is disclosed (see Japanese Patent Laid-Open No. 11-64323, Japanese Patent Laid-Open No. 2002-181802, and Japanese Patent Laid-Open No. 2002-181803). . The color of the water to be measured is qualitatively determined by the abundance ratio between the chelating compound produced by the reaction between the hardness component and the dye contained in the hardness measurement reagent and the unreacted (free) dye. Specifically, when EBT is used as the pigment, the hardness of the water under measurement increases, and the color of the water under measurement changes from the original blue color to the blue purple color. 'Point of view'), and then through reddish violet to red (hereinafter referred to as 'discoloration end point').

Therefore, in the case of discriminating the hardness leakage by paying attention to the color change according to the hardness of the water under measurement, the hardness is determined so that the management hardness falls between the color development start point and the color development end point in advance. After determining the measurement conditions such as the mixing ratio of the EBT in the reagent, the amount of the reagent for hardness measurement at the time of measurement, and the capacity of the water to be measured, the actual measurement is performed.

As described above, when the color change corresponding to the hardness in the water under measurement is used as an index of the hardness leakage, as the color measurement method, visual measurement by human observation, or mechanical measurement by transmittance measurement or absorbance measurement is commonly adopted. In the case of visual measurement, it is judged that hardness leakage occurred when the color of the water under measurement changed from blue to red. In the case of mechanical measurement, the hardness is directly displayed on the measuring instrument based on a calibration curve indicating the relationship between hardness and transmittance (or absorbance), and when the hardness reaches the control hardness, hardness leakage occurs. To judge. Regardless of which measurement method is adopted, it is desirable to have a sensitive color change near the control hardness in order to reliably determine the hardness leak.

However, in the conventional reagent for measuring hardness, since the color change start point and the color change end point (hereinafter referred to as 'color change width') are wide and the color change near the management hardness is dull, the visual measurement through colorimetric measurement is performed. Individual differences occur in the determination of mild leakage.

The problem to be solved by the present invention is to realize a hardness measurement reagent that is sensitively discolored in the vicinity of the management hardness.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, when the chelate compound produced | generated by the reaction of the hardness component and the pigment | dye contained in the hardness measurement reagent, and the pigment | dye which does not react exist in a specific ratio, the number of measured objects will discolor. The above problem can be solved by using a hardness measurement reagent containing an alkali metal salt of a specific chelating agent which reacts with the hardness component and generates a chelating compound by first identifying the quantitative relationship that the color is blue and purple. The present invention was completed.

That is, the invention according to claim 1 is characterized by containing an alkali metal salt of a dye, triethanolamine, a glycol compound, and a chelating agent selected from EBT or calmagite.

The invention according to claim 2 is characterized in that, in addition to the configuration of claim 1, the chelating agent is an organic aminocarboxylic acid.

The invention according to claim 3 is characterized in that the reagent for hardness measurement of claim 1 or 2 is constituted by one liquid.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described. The hardness measuring reagent of the present invention is characterized in that it is a liquid solution and non-aqueous, and contains an alkali metal salt of a chelating agent in addition to the dye, triethanolamine, and glycol compound selected from EBT or calmagite.

EBT or chalmagite is a pigment which is clearly discolored from blue to red by forming a chelating compound with a hardness component in the pH range of an alkali, and can be used individually or in mixture, respectively. Although the mixing ratio of the dye is not particularly limited, the hardness measuring reagent is added when the concentration of the hardness measuring reagent in the water under measurement is 0.24% by weight, in view of sharply discoloring the water under measurement. 0.1-1.0 weight% is preferable, and 0.1-0.5 weight% is more preferable.

Triethanolamine is used to stabilize the color development of pigments by maintaining a pH of about 10. The blending ratio of triethanolamine is not particularly limited, but from the viewpoint of inhibiting freezing of triethanolamine in the reagent and maintaining the reagent at an appropriate viscosity, 10 to 80% by weight of the hardness measurement reagent is preferable. More preferably 30 to 50% by weight.

The glycol compound is used as a solvent of the hardness measurement reagent. As a glycol compound, ethylene glycol, propylene glycol, diethylene glycol, etc. are mentioned, for example, These can be used individually or in mixture of 2 or more types. Among these, ethylene glycol is particularly preferable from the viewpoint of suppressing decomposition of the dye and preventing freezing of triethanolamine. Although the compounding ratio of a glycol compound is not specifically limited, From a viewpoint of making it act as an antifreeze in a reagent, 10-80 weight% is preferable and 30-50 weight% is more preferable in a hardness measurement reagent.

As the chelating agent constituting the alkali metal salt of the chelating agent, an organic chelating agent or an inorganic chelating agent can be used. Examples of the organic chelating agent include aminocarboxylic acids such as ethylenediamine tetraacetic acid (EDTA), trans-1, 2-diaminocyclohexane tetraacetic acid (GEDTA), citric acid, gluconic acid, and the like. Or two or more types can be mixed and used. Examples of the inorganic chelating agent include phosphoric acid compounds such as pyrophosphoric acid, polyphosphoric acid and metaphosphoric acid. In these, an organic chelating agent is preferable from a viewpoint of the chelate formation ability which reacts preferentially with a hardness component compared with a pigment, and aminocarboxylic acid is preferable among organic chelating agents. Among aminocarboxylic acids, EDTA is particularly preferable in view of the above chelate formation ability and economic efficiency.

As an alkali metal which comprises the alkali metal salt of a chelating agent, Na and K are mentioned, for example. Examples of the alkali metal salt of EDTA include EDTA-Na, EDTA-K, EDTA-2Na, EDTA-2K, EDTA-3Na, EDTA-3K, EDTA-4Na, EDTA-4K, and the like. From the standpoint of excellent solubility when added to water, EDTA-2Na, EDTA-3Na and EDTA-4Na are particularly preferred. The blending ratio of the alkali metal salt of the chelating agent is not particularly limited, but from the viewpoint of sharply discoloring the water to be measured near the management hardness, it can be added to the management water-0.1 to 2.0 ppm correspondingly. It is preferable to be contained in the hardness measurement reagent.

In addition, the hardness measurement reagent of the present invention may include a cation exchanger having an alkali metal in counter ions instead of or mixed with an alkali metal salt of a chelating agent. As such a cation exchanger, it is preferable to have a functional group with a small dissociation constant of a hardness component, For example, sodium styrene sulfonate etc. are mentioned. It is preferable that the compounding ratio of this cation exchange agent is the compounding ratio similar to the alkali metal salt of a chelating agent.

In addition to the alkali metal salts of dyes, triethanolamines, glycol compounds and chelating agents, the hardness measuring reagents of the present invention include, for example, masking agents, sensitizers, antideterioration agents and antifoaming agents within the range of not impairing the effects of the present invention. Additives, such as these, can be mix | blended suitably. The masking agent stabilizes the color development of the water under measurement by forming a complex with an interfering ion (for example, Fe, Mn, Al, etc.) in the water under measurement, and examples thereof include triethanolamine and KCN. Triethanol amine is preferably used from the viewpoint of stability when drained. The sensitizer increases or decreases the color reproducibility of pitch-return by replacing Ca ²⁺ in the water under measurement with Mg ²⁺ . For example, EDTA-Mg is preferably used. Although the mixing ratio of the sensitizer is not particularly limited, it is preferably included in the hardness measurement reagent so that the water can be added more than the equivalent of the control hardness to the water to be measured from the viewpoint of sharply discoloring the water to be measured near the control hardness. Do. The deterioration inhibitor prevents deterioration of the dye even when the hardness measurement reagent is left at a high temperature of 50 ° C or higher. For example, potassium sorbate is preferably used. A defoamer removes the bubble in the water under measurement contained in a measuring container, and a nonionic surfactant (for example, polyoxyethylene octylphenyl ether) is used preferably.

The reagent for hardness measurement of the present invention can be produced by uniformly mixing a dye, an alkali metal salt of a triethanolamine, a glycol compound and a chelating agent, and an additive as necessary. For example, after uniformly mixing the glycol compound and the triethanol amine, the alkali metal salt of the chelate compound and the additives are added and mixed in this order as necessary, and finally, the reagent for hardness measurement is added by adding and mixing the dye. It can manufacture.

In addition, the hardness measurement reagent of the present invention can be mixed with a dye, a triethanolamine, a glycol compound, and an alkali metal salt of a chelating agent to form a one-liquid reagent, and the hardness in the water under measurement can be measured. This one-liquid reagent means the hardness measurement reagent containing the component required for hardness measurement and made into one solution. Therefore, when using this hardness measurement reagent, handling and use are simpler and complicated measurement procedures are unnecessary as compared with the case where each component is added and mixed individually.

Next, the present inventors explain the fact that the color change of the water to be measured when the conventional hardness measurement reagent without mixing the alkali metal salt of the chelating agent is added to the water to be measured, and based on this fact, The effect of this invention and the preferable application method are demonstrated. First, when a hardness measurement reagent using EBT as a dye is added to the water to be measured without a hardness component, the pigment included in the hardness measurement reagent is not reacted and is present in an unreacted state. The number is blue. When the resulting chelate compound and unreacted dye are present in a molar ratio of chelate compound to unreacted dye = 20 to 30:80 to 70, the number of measured objects is changed from blue to blue violet. In addition, as the abundance ratio of the chelate compound to the unreacted pigment increases, the water to be measured changes color from blue purple to reddish purple. When all unreacted pigment reacts with the hardness component and only the chelate compound is present, the water to be measured becomes red. It reaches the end point of discoloration.

From the point of view of the amount of dye added to the water to be measured, when 20 to 30% (color discoloration ratio) of the added dye reacts with the hardness component to produce a chelating compound, the water to be measured discolors to produce a blue-purple color. It can be said that when 100% of the added dyes produced a chelating compound, the water to be measured finished discoloration to become red. Therefore, assuming that 1 mg / l (i.e., 1 ppm) is set as the management hardness, if a pigment corresponding to 1 ppm of hardness is added to the water to be measured, 0.2 to 0.3 ppm of hardness is used as the starting point of discoloration. Since the number of measurements starts to discolor in blue violet, the discoloration width from the discoloration start point (hardness 0.2 to 0.3 ppm) to the discoloration end point (hardness 1 ppm) is as much as 0.7 to 0.8 ppm of hardness.

In other words, if a dye amount corresponding to diarrhea management hardness is added to the water to be measured, the measured water starts discoloration at a hardness of 20 to 30% of the control hardness. When the color of the measurement water is measured, it is difficult to determine whether the hardness is close to the management hardness or considerably lower than the management hardness. Therefore, in order to reliably perform such a judgment, it is necessary to narrow the discoloration width, and by narrowing the discoloration width, the hardness leakage can be reliably discriminated.

Therefore, in the present invention, as a constituent of the hardness measurement reagent, an alkali metal salt of a chelating agent is blended so that the chelating agent produces a hardness component and a chelating compound in the water to be measured in preference to the pigment, and the remaining hardness component reacts with the pigment. The ability to produce chelating compounds narrows the discoloration width and causes the color of the subject to be sensitively discolored near the control hardness.

Specifically, assuming that 1 ppm is set as the management hardness, when the alkali metal salt of the chelating agent corresponding to the hardness of 0.5 ppm and the pigment corresponding to the hardness of 0.5 ppm are added to the water to be measured, the alkali metal salt of the chelating agent becomes the hardness. After reacting with the hardness component equivalent to 0.5 ppm preferentially to produce a chelate compound, the remaining hardness component reacts with the pigment. The discoloration start point at this time is 0.6 to 0.65 ppm, and the discoloration end point is 1 ppm. Therefore, the color change width is about 0.35 to 0.4 ppm. Comparing the above two examples with or without the alkali metal salt of the chelating agent, when the alkali metal salt of the chelating agent is added to the reagent for hardness measurement, the discoloration width is narrowed by about 0.37 to 0.42 ppm. That is, in the latter example, the discoloration width is narrowed by bringing the discoloration start point closer to the discoloration end point while the discoloration end point is the same as the former. As described above, in the present invention, the discoloration width can be freely set by appropriately changing the compounding ratio of the alkali metal salt and the dye of the chelating agent, thereby making it possible to sharply discolor the water under the management hardness. The effect of the present invention is remarkable as the management hardness is set higher, and the compounding amount of the dye can also be reduced as compared with the conventional hardness measurement reagent.

In order to increase the hardness measurement accuracy by using the hardness measurement reagent of the present invention, the concentration of the pigment concentration contained in the hardness measurement reagent, the alkali metal salt concentration of the chelating agent, the amount of the hardness measurement reagent added at the time of measurement, It is preferable to determine the measurement conditions such as the capacity beforehand and then measure them. Specifically, when a reagent for hardness measurement is added to the water to be measured, it is operated to contain 0.00024 to 0.0024% by weight of the pigment, 0.05% by weight or more of the triethanolamine, and 0.00006 to 0.0012% by weight of the alkali metal salt of the chelating agent. It is desirable to. Moreover, as for the density | concentration in the reagent for hardness measurement of a pigment | dye, the density | concentration calculated by following Formula is more preferable.

As described above, when the hardness measurement reagent of the present invention is used, it is possible to sharply discolor the water to be measured near the management hardness, and therefore it is particularly suitable for visual measurement through colorimetric application, but it is also applicable to mechanical measurement as well. connect. In addition, in this invention, all the water supply, water in a cold / hot water system, a boiler water, etc. until it supplies to a cold heat equipment can be made into the hardness measurement object. Therefore, for example, the raw water before passing through the hard water softening device is not limited to the softened water passing through the hard water softening device.

EXAMPLE

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

(Preparation of inspection)

As shown in Table 1, the hardness was 0 mg / L, 0.6 mg / L, 0.8 mg / L, 1.0 mg / L, 1.2 mg / L, 1.4 mg / L, 1.6 mg / L, 2.0 mg / L and 4.0 A check was prepared with nine levels of mg / l and three levels of M alkalinity of 5 mg / l, 40 mg / l and 120 mg / l. In addition, when adjusting the hardness, in order to see the color difference when the relative ratio of Ca ²⁺ and Mg ²⁺ is different, the same hardness so that each molar ratio becomes Ca ²⁺ : Mg ²⁺ = 4: 1, 1: 2. Two types of checks with different relative ratios of Ca ²⁺ and Mg ²⁺ were prepared. When preparing the inspection, the hardness was confirmed by spectroscopic analysis, M alkalinity was confirmed by titration using 1/50 N sulfuric acid.

Preparation of Reagent for Hardness Measurement

EBT, triethanolamine, ethylene glycol, EDTA-Na, and EDTA-4Na were each mix | blended so that it might become the composition shown in Table 2, and four types of hardness measurement reagents were prepared by stirring well and melt | dissolving.

(Examples 1-5 and Comparative Examples 1-3)

50 ml of the test was added to a 100 ml beaker, and 121 µl of the hardness measurement reagent was added dropwise to the test using a micro syringe, and the beaker was gently shaken. The inspection developed immediately. One minute after color development, color was observed. The results are shown in Table 1. In addition, the starting point of discoloration, the end point of discoloration, and the discoloration width of each test zone derived based on the results of Table 1 are shown in Table 3. In this test, the hardness equivalent concentrations of EBT and EDTA-4Na in the hardness measurement reagents dropped in each test were calculated in terms of CaCO ₃ , and 2.2 mg / L (0.7 mg / L for EDTA-4Na and EBT for Reagent 1). 1.5 mg / l), 3.5 mg / l for Reagent 2 (1.0 mg / l for EDTA-4Na, 2.5 mg / l for EBT), and 2.5 mg / l for Reagent 3 and Reagent 4 (2.5 mg for EBT), respectively. / l).

TABLE 1

 reagent Water quality Hardness (mg / ℓ) M alkalinity (mg / L)  Ca: Mg  0  0.6  0.8  1.0  1.2  1.4  1.6  2.0  4.0 Example 1 Reagent 1 120 1: 2 blue blue blue blue Blue purple Fuchsia Reddish purple Red Red Example 2 Reagent 1 40 1: 2 blue blue blue blue Blue purple Fuchsia Reddish purple Red Red Example 3 Reagent 1 5 1: 2 blue blue blue blue Blue purple Cock Reddish purple Red Red Example 4 Reagent 1 40 4: 1 blue blue blue blue Blue purple Fuchsia Reddish purple Red Red Example 5 Reagent 2 40 4: 1 blue blue blue blue blue blue Blue purple Fuchsia Red Comparative Example 1 Reagent 3 40 1: 2 blue blue Blue purple Blue purple Blue purple Fuchsia Fuchsia Red purple Red Comparative Example 2 Reagent 3 40 4: 1 blue blue blue blue blue blue blue blue Blue purple Comparative Example 3 Reagent 4 40 4: 1 blue blue Blue purple Blue purple Blue purple Fuchsia Fuchsia Red purple Red

TABLE 2

Ingredient Reagent 1 Reagent 2 Reagent 3 Reagent 4 Composition of Reagent for Hardness Measurement (wt%) EBT 0.26 0.44 0.44 0.44 Triethanolamine 49.31 49.19 49.78 49.13 Ethylene glycol 49.31 49.19 49.78 49.13 EDTA-Mg 1.0 1.0 0 1.3 EDTA-4Na 0.12 0.18 0 0

TABLE 3

 reagent Water quality Start of discoloration (mg / ℓ) Discoloration end point (mg / ℓ) Discoloration width (mg / ℓ) M alkalinity (mg / L) Ca: Mg Example 1 Reagent 1 120 1: 2 1.1 2.2 1.1 Example 2 Reagent 1 40 1: 2 1.1 2.2 1.1 Example 3 Reagent 1 5 1: 2 1.0 2.0 1.0 Example 4 Reagent 1 40 4: 1 1.1 2.2 1.1 Example 5 Reagent 2 40 4: 1 1.6 3.5 1.9 Comparative Example 1 Reagent 3 40 1: 2 0.9 3.7 2.8 Comparative Example 2 Reagent 3 40 4: 1 2.9 7.5 4.6 Comparative Example 3 Reagent 4 40 4: 1 0.6 2.5 1.9

From Table 3, it turns out that Examples 1-4 are narrow in color change width compared with Comparative Examples 1-3. From this, referring to this example, for example, when the control hardness is set to 2.0 mg / l, the EDTA-4Na is contained in the reagent for hardness measurement, so that the inspection is discolored sensitively near the hardness of 2.0 mg / l. This makes it possible to reliably determine the hardness leak. In addition, when the reagents 1 (Examples 1 to 3) and the reagents 2 (Example 5) are compared, it is understood that the discoloration start point and the discoloration end point are different from each other, and the discoloration width of the reagent 1 is narrower. Therefore, referring to this embodiment, by changing the blending ratio of EDTA-4Na and EBT, the color development start point, color development end point and color fading width can be freely controlled.

According to the present invention, the number of measured objects becomes sensitively discolored in the vicinity of the management hardness, thereby making it possible to reliably determine the hardness leak. More specifically, the alkali metal salt of the chelating agent produces a hardness component and a chelating compound in the water to be measured in preference to the pigment, and the remaining hardness component reacts with the pigment to produce a chelating compound, resulting in a narrow discoloration width. Sensitivity discolors in the vicinity. In addition, since the reagent for hardness measurement is composed of one liquid, the handling and use of the reagent can be simplified.

Claims (3)

A reagent for measuring hardness, which comprises an alkali metal salt of a dye selected from eryochrome black tee or calmagite, a triethanolamine, a glycol compound, and a chelating agent. The method of claim 1, A hardness measurement reagent, wherein the chelating agent is an organic aminocarboxylic acid. The hardness measurement reagent according to claim 1 or 2, wherein the hardness measurement reagent is constituted by one liquid.