JP4214938B2 - Reagent for hardness measurement - Google Patents

Description

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

As is well known, the hardness of raw water such as industrial water and domestic water is necessary to prevent the scale from adhering to the water supply line to the cooling equipment such as boiler, water heater or cooler. A device for removing the components (Ca ²⁺ and Mg ²⁺ ) is connected. For example, a hard water softening device using an ion exchange resin is connected to a water supply line, and hardness components (Ca ²⁺ and Mg ²⁺ ) in raw water are removed. Substituting with Na ⁺ , the resulting softened water is supplied to cold heat equipment as feed water.

When the water softening device is used, if the ion exchange resin contained in the device is deteriorated or if the ion exchange resin is not sufficiently regenerated, the hardness component in the feed water is replaced with Na ⁺ . Becomes insufficient. Therefore, it is necessary to set the hardness allowed in advance according to the hardness of the raw water in the area or place where the cooling / heating equipment is installed, and periodically inspect the hardness of the feed water that has passed through the water softening device. . If the hardness of the water supply exceeds the upper limit of the allowable value (hereinafter referred to as “management hardness”), it is determined that a hardness leak has occurred, and the ion exchange resin is replaced or regenerated. Is treated within a predetermined hardness range.

  As a method for discriminating the hardness of the feed water, for example, a non-aqueous hardness measuring reagent containing Eriochrome Black T (EBT) as a pigment is added to the test water sampled from the water supply, and the hue of the test water is determined. A method of using an index is disclosed (see Patent Documents 1, 2, and 3). The hue of this test water is qualitatively determined by the abundance ratio of the chelate 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 dye, the hue of the test water changes from the original blue to blue-violet as the hardness in the test water increases (hereinafter, the hardness when the blue-purple hue is exhibited). Is referred to as “color change start point”, and further passes reddish purple to red (hereinafter, the hardness when a red hue is exhibited is referred to as “color change end point”).

  Therefore, when discriminating the hardness leakage by paying attention to the hue change according to the hardness in the test water, the management hardness is determined in advance, and the management hardness falls between the color change start point and the color change end point. In addition, the actual inspection work is performed after determining the blending ratio of EBT in the hardness measurement reagent, the addition amount of the hardness measurement reagent at the time of inspection, and the capacity of the test water.

  As described above, when the hue change corresponding to the hardness in the test water is used as an indicator of hardness leakage, a visual inspection by human observation or a mechanical inspection by transmittance measurement or absorbance measurement is usually employed as a hue inspection method. ing. When visual inspection is performed, it is determined that a hardness leak has occurred when the color of the test water reaches blue-purple or red. Also, when performing mechanical inspection, the hardness is displayed directly 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, a hardness leak occurs. Judge that Regardless of which inspection method is used, in order to reliably determine hardness leakage, the color of the test water is not disturbed by the interfering substances in the test water, and the test water may exhibit a hue corresponding to the hardness. desirable.

However, according to the study of the present inventor, when the residual chlorine concentration in the feed water is 1.5 mg / liter or more, the conventional hardness measuring reagent interferes with the color development of the test water, and decolorization compared with the hue to be originally exhibited. It was confirmed to exhibit a yellow hue. This is a problem when the visual inspection is performed because it has a large effect on the hue of the test water, and also when the mechanical inspection is performed, there is a difference between the actual hardness and the measured hardness. There is. Therefore, further improvement has been desired in order to ensure the hardness leak inspection of the water supply, particularly in water quality with a high residual chlorine concentration.
Japanese Patent Laid-Open No. 11-64323 JP 2002-181802 A JP 2002-181803 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a hardness measurement reagent that is not affected by the residual chlorine concentration when measuring hardness.

  As a result of intensive studies to solve the above problems, the present inventor has found that the above problems can be solved by using a hardness measurement reagent containing a residual chlorine immobilization component that reacts with residual chlorine to generate bound chlorine, The present invention has been completed.

That is, the hardness measuring reagent of claim 1 contains a dye selected from Eriochrome Black T (EBT) or Karmagite, a triethanolamine, a glycol compound and a residual chlorine fixing component, and the residual chlorine fixing component is 1 or more selected from the group consisting of primary amines, secondary amines and salts thereof.

  According to the hardness measuring reagent of the present invention, the color development of the test water is hardly obstructed regardless of the residual chlorine concentration in the feed water, and the test water exhibits a hue corresponding to the actual hardness.

  The hardness measurement reagent of the present invention is a one-component, non-aqueous system and contains a residual chlorine fixing component in addition to a dye selected from Eriochrome Black T (EBT) or Karmagite, triethanolamine, and a glycol compound. Characterized by points.

  EBT or karmagite is a pigment that changes its color clearly from blue to red by forming a chelate compound with a hardness component in the alkaline pH region, and can be used alone or in combination. The blending ratio of the dye is not particularly limited, and is usually 0.1 to 1.0% by weight, preferably 0.1 to 0.5% by weight in the reagent for hardness measurement. By setting the blending ratio of the pigment within such a range, the test water can be made to have a hue corresponding to the actual hardness regardless of the residual chlorine concentration.

  Triethanolamine is used to stabilize the color development of the dye by maintaining the pH at around 10. The mixing ratio of triethanolamine is not particularly limited, and is usually 10 to 80% by weight, preferably 30 to 50% by weight in the reagent for hardness measurement. By setting the blending ratio of triethanolamine within such a range, freezing of triethanolamine in the reagent can be suppressed and the reagent can be kept at an appropriate viscosity.

  The glycol compound is used as a solvent for a hardness measurement reagent. Examples of the glycol compound include ethylene glycol, propylene glycol, diethylene glycol and the like, and these can be used alone or in admixture of two or more. Among these, ethylene glycol is particularly preferable from the viewpoint of suppressing decomposition of the dye and preventing freezing of triethanolamine. The blending ratio of the glycol compound is not particularly limited, and is usually 10 to 80% by weight, preferably 30 to 50% by weight in the reagent for hardness measurement. By setting the blending ratio of the glycol compound within such a range, the glycol compound can act as an antifreeze in the reagent.

  The residual chlorine immobilization component is a compound that reacts with the residual chlorine to generate bonded chlorine such as chloramine, chloroimine, chloroimide, and the like. Examples of the residual chlorine fixing component include primary amines, secondary amines, salts thereof, and ammonium salts, and these can be used alone or in admixture of two or more. Examples of primary amines include alkyl alcohol amines (eg, monoethanolamine), linear alkylamines (eg, butylamine), cyclic alkylamines (eg, cyclohexylamine), aromatic amines (eg, aniline), amino acids, and the like. Can be mentioned. Secondary amines include, for example, alkyl alcohol amines (eg, diethanolamine), linear alkylamines (eg, diethylamine), cyclic alkylamines (eg, azacyclohexane [piperidine]), aromatic amines (eg, diphenylamine), amino acids Etc. Among these, alkyl alcohol amines (for example, monoethanolamine, diethanolamine) are particularly preferable from the viewpoint of ensuring the color stability of the test water corresponding to the hardness in the test water without being affected by the residual chlorine concentration.

  Examples of primary amine salts include alkyl alcohol amines (eg, monoethanolamine), linear alkylamines (eg, butylamine), cyclic alkylamines (eg, cyclohexylamine), aromatic amines (eg, aniline), amino acids, etc. (For example, hydrochloride, sulfate, acetate, oxalate, etc.). Secondary amine salts include, for example, alkyl alcohol amines (eg, diethanolamine), linear alkylamines (eg, diethylamine), cyclic alkylamines (eg, azacyclohexane [piperidine]), aromatic amines (eg, diphenylamine), amino acids Acid salts (eg, hydrochloride, sulfate, acetate, oxalate, etc.). Examples of ammonium salts include ammonium chloride, ammonium acetate, ammonium sulfate, ammonium bromide, and ammonium oxalate.

  The blending ratio of the residual chlorine fixing component is not particularly limited, and is usually 0.3 to 3.0% by weight, more preferably 0.5 to 2.0% by weight in the reagent for measuring hardness. By setting the blending ratio of the residual chlorine fixing component within such a range, the test water can have a hue corresponding to the actual hardness regardless of the residual chlorine concentration.

In addition to the dye, triethanolamine, glycol compound and residual chlorine fixing component, the hardness measuring reagent of the present invention includes, for example, a masking agent, a sensitizer, and an anti-degradation agent as long as the effects of the present invention are not impaired. , Additives such as antifoaming agents can be appropriately blended. The masking agent stabilizes the color development of the test water by forming a complex with interfering ions (for example, Fe, Mn, Al, etc.) in the test water, and examples thereof include triethanolamine, KCN, etc. Among them, triethanolamine is preferably used from the viewpoint of safety when drained. The sensitizer is for sensitizing the color development of the test water by substituting Ca ²⁺ in the test water with Mg ²⁺ . For example, EDTA-Mg is preferably used. The deterioration preventing agent prevents the deterioration of the dye even when the hardness measurement reagent is placed at a high temperature of 50 ° C. or higher. For example, potassium sorbate is preferably used. The antifoaming agent is for defoaming bubbles in the test water contained in the measurement container, and for example, a nonionic surfactant (for example, polyoxyethylene octylphenyl ether) is preferably used.

  The hardness measuring reagent of the present invention can be produced by uniformly mixing the additive, if necessary, with a dye, triethanolamine, a glycol compound and a residual chlorine fixing component. For example, a uniform hardness-measuring reagent is produced by adding and mixing glycol compound, triethanolamine and residual chlorine-fixing component, if necessary, in this order, and finally adding and mixing the dye. be able to.

  In the present invention, when the hardness measuring reagent produced as described above is added to test water that does not contain hardness components, the residual chlorine concentration in the test water is, for example, about 10 mg / liter, and the color development of the test water is not hindered. The hue of the test water can be maintained at a normal blue color. Therefore, if the reagent for measuring hardness of the present invention is used, the color development of the test water is not disturbed even for the test water having a particularly high residual chlorine concentration, and the hue of the test water is set to a hue corresponding to the hardness of the test water. be able to. In addition, in order to increase the accuracy of the hardness inspection, the inspection should be performed after the inspection conditions such as the concentration of the dye contained in the hardness measurement reagent, the added amount of the hardness measurement reagent at the time of inspection, and the volume of sample water to be collected are determined in advance. It is preferable to do. Specifically, when the hardness measurement reagent is added to the test water, the dye is contained in the test water at 0.00024 to 0.0024% by weight, triethanolamine is 0.05% by weight or more, and the residual chlorine fixing component is added. It is preferable to operate so as to contain 0.0009 to 0.009% by weight (more preferably 0.0015 to 0.006% by weight).

  As described above, the hardness measuring reagent of the present invention is particularly suitable for visual inspection by observing hue, but can be similarly applied to mechanical inspection for measuring absorbance or transmittance. Moreover, in this invention, all the water supply until it supplies to cold / heat equipment, the water in a cold / hot water system, or boiler water can be made into the test object of hardness. Therefore, for example, not only the softened treated water that has passed through the above-described hard water softening device, but also raw water before passing through the hard water softening device can be a test object for hardness.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples.

(Effect of residual chlorine concentration when using a conventional reagent for hardness measurement)
Prior to the examples, the effect of residual chlorine concentration on the hue of test water was examined when a conventional hardness measuring reagent was used. First, sodium hypochlorite is dissolved in distilled water, and the concentration of sodium hypochlorite is 1.0 mg / liter, 1.5 mg / liter, 2.0 mg / liter, 3.0 mg / liter, 5.0 mg. / Liter of measuring water was prepared, the number of 100 ml beakers corresponding to the measuring water was prepared, and 50 ml of measuring water was put into the beaker. Next, EBT, triethanolamine, ethylene glycol, and EDTA-Mg were blended so as to have the composition of reagent 5 in Table 1, and dissolved by stirring well to prepare a conventional hardness measurement reagent. . And 120 microliters of reagent 5 was dripped at the said measurement water, Then, measurement water was stirred. The measuring water developed color immediately, and the hue 1 minute after the color development was observed. The results are shown in Table 2.

  From Table 2, it can be seen that the higher the residual chlorine concentration in the measuring water, the more disturbed the coloring of the measuring water, and the hue of the measuring water is decolored when the residual chlorine concentration is 1.5 mg / liter or more.

(Examples 1-4)
Prepare the reagent by mixing EBT, triethanolamine, ethylene glycol, EDTA-Mg, and monoethanolamine (or diethanolamine) so that they have the composition of Reagents 1 to 4 in Table 1, and stir well to dissolve. did. Next, 100 ml beakers of the number corresponding to the reagent were prepared, and 50 ml of distilled water was added to each to make measurement water. Then, 120 microliters of the reagent was added to the measurement water, and the measurement water was colored blue by stirring. Subsequently, sodium hypochlorite was dissolved in distilled water to prepare chlorine water having a residual chlorine concentration of 200 mg / liter. After adding 250 microliters of the prepared chlorinated water to the blue measuring water and stirring, the hue of the measuring water was observed. When the hue of the measurement water was blue, 250 microliters of chlorine water was added to the measurement water again, and the same operation as described above was performed, and the same operation was repeated until the measurement water showed yellow. In this test, the residual chlorine concentration in the measured water when the measured water showed yellow was defined as the allowable residual chlorine concentration. The larger the value of the allowable residual chlorine concentration, the less the reagent used is affected by the residual chlorine concentration. The results are shown in Table 3.

  From Table 3, in all of Examples 1 to 4, the residual chlorine allowable concentration exceeded 10 mg / liter. Therefore, if a hardness measuring reagent containing monoethanolamine or diethanolamine is used as the residual chlorine immobilization component, the hue of the test water has almost no effect even if the test water contains about 10 mg / liter of residual chlorine. I understand that I do not receive. Further, from the comparison between Example 1 and Example 3 or Example 2 and Example 4, it is considered that the effects of monoethanolamine and diethanolamine are almost the same.

Claims (1)

A hardness measuring reagent comprising a dye selected from Eriochrome Black T (EBT) or Karmagite, triethanolamine, a glycol compound and a residual chlorine fixing component ,
A reagent for measuring hardness, wherein the residual chlorine fixing component is at least one selected from the group consisting of primary amines, secondary amines and salts thereof.