KR101100556B1 - Method of determining chelating agent and determination kit for chelating agent - Google Patents

Abstract

At the site where the hot air heater is installed, the concentration of the water treatment agent can be easily known. The measuring method of the chelating agent concerning this invention is the process of taking a sample water, the process of adding the 1st chemical liquid containing a metal indicator and the 2nd chemical liquid containing a pH adjuster, respectively, to the sampled sample water, 1 A third chemical solution containing a metal salt for discoloring the metal indicator is added dropwise to the number of samples to which the chemical solution and the second chemical solution are added, and the number of drops until the number of samples changes color is counted. And a step of specifying the concentration of the chelating agent in the sample water based on the dropping number of the third chemical liquid. In addition, the measuring kit of the chelating agent according to the present invention includes a first container containing a first chemical liquid containing a metal indicator, a second container containing a second chemical liquid containing a pH adjuster, and a metal salt for discoloring the metal indicator. The 3rd container which contains the 3rd chemical liquid containing is provided.

Hot air conditioner, water treatment agent, chelating agent, first chemical, second chemical, third chemical, measuring kit

Description

METHOD OF DETERMINING CHELATING AGENT AND DETERMINATION KIT FOR CHELATING AGENT}

1 is a graph showing the correlation between the quantitative value of EDTA-2Na by HPLC method and the quantitative value of EDTA-2Na by simple titration method.

The present invention relates to a measuring method of a chelating agent and a measuring kit of a chelating agent, and more particularly, to a measuring method and measuring kit for easily specifying the concentration of a chelating agent contained in water to which a water treatment agent is added.

In hot air heaters, such as a boiler and a cooling tower, in general, in order to suppress corrosion and scale formation of the heat-transfer surface by moisture, adding a water treatment agent to replenishment water is performed. In recent years, in the boiler, as disclosed in Patent Literature 1, a water treatment agent composed of a food additive and containing silica, an alkali agent and a scale inhibitor is used. Here, the said silica is mix | blended for the purpose of forming a film in the said heat transfer surface, and protecting it from corrosion by moisture. The alkali agent is typically a hydroxide of an alkali metal, and is blended for the purpose of adjusting the water to a pH range (pH11 to 12) where the heat transfer surface is hard to corrode. The scale inhibitor is a chelating agent capable of complexing complexes with hardness components (calcium ions and magnesium ions), copper ions, zinc ions and iron ions, which are scale promoting components in the replenishing water. It is mix | blended for the purpose of suppressing scale formation in the contact surface of water and moisture.

The supply amount of the water treatment agent is set such that the concentration of the water treatment agent in the hot air heater is within a predetermined range based on the quality of the replenishment water, the operating conditions of the hot air heater (for example, the concentration ratio in the boiler), and the like. In order to maximize the effect of the water treatment agent, it is important that the concentration of the water treatment agent is maintained in a predetermined range, and when the concentration of the water treatment agent is insufficient or excessive, it is necessary to quickly readjust the supply amount of the water treatment agent. For this reason, it is essential for the maintenance manager and the user to find out the concentration of the water treatment agent regularly at the site where the hot air is installed.

Patent Document 1: JP2003-159597A

By the way, in order to know the concentration of the water treatment agent, trying to quantify all of the components supplied as the water treatment agent separately requires a lot of effort and effort. In addition, when it is going to quantify the specific component supplied as the said water treatment agent, for example, in the case of the water treatment agent disclosed by patent document 1, since a silica forms a film in the said heat-transfer surface, the density calculated from a supply amount, and actually There is a problem that the concentrations of do not match. In addition, since alkali metal hydroxides are produced even when alkali components such as sodium hydrogencarbonate in the replenishment water are thermally decomposed, there is a problem that the concentration calculated from the supply amount and the actual concentration do not coincide particularly with the boiler. For this reason, it was a situation that the concentration of the water treatment agent was not easily known at the site where the hot air was installed.

This invention is made | formed in view of the said situation, The objective is to find out the concentration of a water treatment agent easily in the field | area where a hot air heater was installed.

This invention is made | formed in order to achieve the said objective. A first aspect of the present invention is a method for measuring the concentration of chelating agent in a sample water, comprising the steps of collecting a sample water, a first chemical solution containing a metal indicator in the sample water and a pH adjuster. Adding a second chemical liquid, and dropping a third chemical liquid containing a metal salt that discolors the metal indicator to the number of samples to which the first chemical liquid and the second chemical liquid are added. It includes a step of counting the dropping number to and a step of specifying the concentration of the chelating agent in the sample water based on the dropping number of the third chemical liquid.

According to the first aspect, when the third chemical liquid is dropped into the sample water to which the first chemical liquid and the second chemical liquid are added, the chelating agent preferentially forms a complex with a specific metal ion from the metal salt. When the entire amount of the chelating agent forms a complex with the specific metal ion, the metal indicator forms a complex with an excess of the specific metal ion and the number of samples discolors. Since the supply amount of the specific metal ion until the sample water discolors corresponds to the amount of the chelating agent present, the concentration of the chelating agent is specified based on the dropping number of the third chemical liquid. Therefore, when this measuring method is used, the concentration of the water treatment agent in the hot air can be easily known by using the chelating agent contained in the water treatment agent as an index.

The second aspect of the present invention includes, in the first aspect, a step of further adding a masking agent to the sampled sample water.

According to a second aspect, when the third chemical liquid is added dropwise in the presence of the masking agent, the first iron ion or copper ion complexed with the chelating agent forms a complex with the masking agent preferentially. For this reason, the reaction time until the whole quantity of the said chelating agent forms a complex with the said specific metal ion quickly, and a sample water discolors is shortened. Therefore, using this measuring method, the chelating agent contained in the water treatment agent can be used as an index to quickly and accurately know the concentration of the water treatment agent in the hot air.

In a second aspect of the present invention, the second aspect includes a step of further adding a reducing agent to the sample water collected.

According to the third aspect, when the reducing agent is added, the ferric ions in the sample water are reduced to the ferric ions. And this ferrous ion is sealed with the said masking agent. This prevents the metal indicator from complexing with the ferric ions and causing color development, thereby ensuring the normal color of the sample water. Therefore, using this measuring method, it is possible to more accurately know the concentration of the water treatment agent in the hot air machine by using the chelating agent contained in the water treatment agent as an index.

According to a fourth aspect of the present invention, there is provided a method for measuring the concentration of chelating agent in a sample water, comprising the steps of: collecting a sample water; Adding a third chemical solution containing a metal salt for discoloring the metal indicator to the number of samples to which the first chemical solution and the second chemical solution were added, respectively, and counting the number of drops until the number of samples changed color. And a step of specifying the concentration of the chelating agent in the sample water based on the dropping number of the third chemical liquid, wherein the chelating agent is ethylenediamine tetraacetic acid and its salt, and the metal indicator, the pH adjusting agent and the Metal salts are xylenol orange, nitric acid and bismuth nitrate, respectively.

According to the fourth aspect, when the third chemical is added dropwise to the sample water to which the first and second chemicals are added, ethylenediamine tetraacetic acid (EDTA) preferentially complexes with bismuth ions from bismuth nitrate. To form. When the total amount of EDTA forms a complex with bismuth ions, xylenol orange forms a complex with excess bismuth ions and the number of samples discolors. Since the supply amount of bismuth ions until the sample water discolors corresponds to the amount of EDTA present, the concentration of EDTA is specified based on the dropping number of the third chemical liquid. Therefore, using this measuring method, it is possible to easily know the concentration of the water treatment agent in the hot air machine by using EDTA contained in the water treatment agent as an index.

In a fifth aspect of the present invention, in a fourth aspect, the method further comprises adding a masking agent to the sample water collected, wherein the masking agent is o-phenanthroline.

According to the fifth aspect, when the third chemical solution is dropped in the presence of o-phenanthrol, ferrous ions and copper ions complexed with EDTA preferentially form a complex with o-phenanthrol. For this reason, the reaction time until the whole quantity of EDTA forms a complex with bismuth ion rapidly, and a sample water discolors is shortened. Therefore, using this measuring method, the EDTA contained in the water treatment agent can be used as an index to quickly and accurately know the concentration of the water treatment agent in the hot air.

In a fifth aspect of the present invention, in a fifth aspect, the method further includes adding a reducing agent to the sampled sample water, wherein the reducing agent is ascorbic acid and an alkali metal salt thereof.

According to the sixth aspect, when ascorbic acid or its alkali metal salt is added, the ferric ions in the sample water are reduced to the ferric ions. And this ferrous ion is sealed by o-phenanthrol. For this reason, xylenol orange is prevented from forming a complex with ferric ions and developing color, thereby ensuring the normal color of the sample water. Therefore, using this measuring method, it is possible to more accurately know the concentration of the water treatment agent in the hot air by using EDTA contained in the water treatment agent as an index.

A seventh aspect of the present invention is a chelating agent measuring kit for quantifying the concentration of a chelating agent in a sample water, comprising a first container containing a first chemical solution containing a metal indicator and a second chemical solution containing a pH adjuster. A second container, and a third container containing a third chemical liquid containing a metal salt for discoloring the metal indicator.

According to the seventh aspect, the first chemical is added from the first container to the sample water, and the third chemical is added from the third container after the second chemical is added from the second container. Upon solution, the chelating agent preferentially forms a complex with a specific metal ion from the metal salt. When the entire amount of the chelating agent forms a complex with the specific metal ion, the metal indicator forms a complex with an excess of the specific metal ion and the number of samples discolors. Since the supply amount of the specific metal ion until the sample water discolors corresponds to the amount of the chelating agent present, the concentration of the chelating agent is specified based on the dropping number of the third chemical liquid. Therefore, by using this measurement kit, the concentration of the water treatment agent in the hot air can be easily known by using the chelating agent contained in the water treatment agent as an index.

In an eighth aspect of the present invention, in the seventh aspect, the first chemical liquid or the second chemical liquid further contains a masking agent.

According to the eighth aspect, after the masking agent is added to the sample water with the first chemical liquid or the second chemical liquid, the third chemical liquid is dropped, and the first iron ion complexed with the chelating agent. Inorganic copper ions preferentially form a complex with the masking agent. For this reason, the reaction time until the whole quantity of the said chelating agent forms a complex with the said specific metal ion quickly, and a sample water discolors is shortened. Therefore, using this measurement kit, the chelating agent contained in the water treatment agent can be used as an index to quickly and accurately know the concentration of the water treatment agent in the hot air.

In a ninth aspect of the present invention, in the eighth aspect, the first chemical liquid further contains a reducing agent.

According to the ninth aspect, when the reducing agent is added with the first chemical liquid, the ferric ions in the sample water are reduced to the ferric ions. And this ferrous ion is sealed with the said masking agent. This prevents the metal indicator from forming complexes with the ferric ions, thereby ensuring the normal color of the sample water. Therefore, using this measurement kit, the chelating agent contained in the water treatment agent can be used as an index to more accurately know the concentration of the water treatment agent in the hot air.

In addition, in the eighth aspect of the present invention, the eighth aspect includes a fourth container in which the powdery reducing agent is accommodated.

According to the tenth aspect, when the powdery reducing agent is added from the fourth container, the ferric ions in the sample water are reduced to the ferric ions. And this ferrous ion is sealed with the said masking agent. This prevents the metal indicator from forming complexes with the ferric ions, thereby ensuring a normal color change of the sample water. Therefore, using this measurement kit, the chelating agent contained in the water treatment agent can be used as an index to more accurately know the concentration of the water treatment agent in the hot air.

Embodiment of the Invention

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail. The chelating agent measuring method and measuring kit according to the present invention are used to manage the amount of water treatment agent supplied to a hot air machine represented by a boiler, a cooling tower, or the like. Specifically, the chelating agent blended with the water treatment agent is used as a tracer to specify the concentration of the water treatment agent in the hot air heater, and to determine whether or not the supply amount of the water treatment agent is appropriate based on the water treatment agent concentration.

In the water treatment agent, the chelating agent seals hardness components (calcium ions and magnesium ions), copper ions, zinc ions and iron ions, which are scale promoting components in water, to generate scale on the heat transfer surface of the hot air heater. It is mix | blended in order to suppress. As such a chelating agent, an organic aminocarboxylic acid compound, a tricarboxylic acid compound, an inorganic polymerization phosphoric acid compound, etc. are used, for example.

Specific examples of the aminocarboxylic acid compound include ethylenediamine tetraacetic acid (EDTA) and salts thereof; Nitrilo triacetic acid (NTA) and salts thereof; Hydroxyethylethylenediamine triacetic acid (HEDTA) and its salts; Trans-1,2-diaminocyclohexane tetraacetic acid (CyDTA), its salt, etc. are mentioned. Moreover, citric acid, its salt, etc. are mentioned as a specific example of the said tricarboxylic acid type compound. Moreover, hydroxyethylidene diphosphonic acid (HEDP), its salt, etc. are mentioned as a specific example of the said polymeric phosphoric acid type compound. Among these compounds, alkali metal salts of ethylenediamine tetraacetic acid are preferably used because they are compounds that do not promote scale generation on the heat transfer surface. Among the alkali metal salts of ethylenediamine tetraacetic acid, ethylenediamine tetraacetic acid sodium salt is particularly preferably used because it is a safe compound that can be used as a food additive.

By the way, the said measurement kit is used in order to quantify the density | concentration of the said chelating agent, for example, EDTA in sample water by a titration method. The measuring kit includes a first container containing a first chemical liquid containing a metal indicator, a second container containing a second chemical liquid containing a pH adjuster, and a third chemical liquid containing a metal salt that discolors the metal indicator. A third container is provided.

The first container, the second container, and the third container are containers configured to be capable of dropping a chemical liquid into a sample water while storing the chemical liquid, for example, dropping with a nozzle equipped with a nozzle in a resin bottle. Bottles are available. This dropping bottle with a nozzle is a type of dropping a predetermined amount of a chemical liquid by pressing the body portion of the bottle during use. In addition, the dropper bottle with a dropper in which a dropper is attached to the cap of a bottle can also be used for the said 1st container, the said 2nd container, and the said 3rd container. This dropper dropping bottle is a type of dropping a predetermined amount of chemical liquid after sucking up the chemical liquid in the bottle with the dropper at the time of use. The first container, the second container, and the third container may also use a dropper container in which a dropper is attached separately from the bottle. This dropper container is of a type in which a predetermined amount of chemical liquid is dripped after sucking up the chemical liquid in the bottle with the dropper during use.

The bottle is made of a material (for example, polyethylene or glass) that impurities do not elute from the viewpoint of not contaminating or deteriorating the first chemical liquid, the second chemical liquid and the third chemical liquid during storage. It is preferable that it is shielded. Moreover, it is preferable that the capacity | capacitance of the said bottle is set in the range of 25-100 ml from the viewpoint of the ease of handling and the ease of carrying.

Subsequently, the first chemical liquid, the second chemical liquid and the third chemical liquid will be described. First, the first chemical liquid will be described. The metal indicator contained in the first chemical liquid is a dye-based chelating substance which is discolored by reacting with the metal salt contained in the third chemical liquid, and is used for detecting the end point in the titration operation. In a proper operation for which the chelating agent is a quantitative target, metal ions constituting the metal salt (hereinafter, referred to as 'specific metal ions' in order to distinguish it from metal ions included in the sample water) are preferentially associated with the chelating agent. It is necessary to form a complex. For this reason, the said metal indicator is selected from the chelating substance whose stability constant with the said specific metal ion is smaller than the said chelating agent. As such a chelating substance, for example, when EDTA is the quantitative target, xylenol orange (chemical name: 3,3'-bis [N, N-di (carboxymethyl) aminomethyl] -o-cresolsulfophthalein) , Disodium salt) or methyl thymol blue (chemical name: 3,3'-bis [N, N-di (carboxymethyl) aminomethyl] thymol sulfophthalein, disodium salt) can be used.

Content of the said metal indicator in a said 1st chemical liquid is not specifically limited because it operates so that a predetermined amount of said metal indicator may be supplied, when adding the said 1st chemical liquid to a sample water, as mentioned later. Usually, it can set suitably in 0.1-0.6 weight% from a viewpoint of solubility and economy.

Further, the first chemical liquid may contain a masking agent in order to seal the ferrous ions and copper ions in the sample water. Since ferrous ions and copper ions derived from replenishing water, piping materials and the like are usually strongly ignited with the chelating agent, the substitution with the specific metal ions is unlikely to occur, and a long time is determined for determination of the end point in the proper operation. It may be necessary. On the other hand, when the masking agent is contained in the first chemical solution, the first iron ions and copper ions preferentially form a complex with the masking agent. For this reason, the reaction time until the whole quantity of the said chelating agent forms a complex with the said specific metal ion quickly, and a sample water discolors is shortened. Here, the masking agent has a greater stability constant with ferrous ions and copper ions than the chelating agent, and does not inhibit the identification of the color change of the metal indicator when the ferrous ions and the copper ions are sealed. Is not selected from chelating substances. As such a chelating substance, o-phenanthroline or the like can be used when EDTA is to be quantified.

Content of the said masking agent in a said 1st chemical liquid is not specifically limited because it operates so that a predetermined amount of said masking agent may be supplied, when adding the said 1st chemical liquid to a sample water, as mentioned later. Usually, from a viewpoint of solubility and economy, it can set suitably in 0.5 to 5 weight%.

In addition, the first chemical solution may contain a reducing agent in order to prevent the metal indicator from complexing with the ferric ions in the sample water. For example, xylenol oranges in an acidic solution are yellow at pH 6 or lower, but turn blue when complexed with ferric ions. For this reason, normal color change does not occur during the titration operation, and the chelating agent cannot be quantified. On the other hand, when the ferric ions are reduced to ferrous ions, xylenol oranges exhibit the original color. Here, the reducing agent is selected from reducing materials which have a function of reducing ferric ions to ferrous ions and do not cause turbidity, precipitation and coloring in the sample water. As such a reducing substance, ascorbic acid and its alkali metal salt, the alkali metal salt of sulfite, the alkali metal salt of bisulfite, hydroxylamine chloride, etc. can be used, for example.

Content of the said reducing agent in a said 1st chemical liquid is not specifically limited because it operates so that a predetermined amount of the said reducing agent may be supplied, when adding the said 1st chemical liquid to sample water, as mentioned later. Usually, it can set suitably in 0.1-10 weight% from a solubility and economical viewpoint.

The said 1st chemical liquid can be manufactured by melt | dissolving the said metal indicator and other additives (the said masking agent and the said reducing agent) uniformly in water or alcohol which is a solvent. For example, in the first chemical liquid for which EDTA is to be quantified, xylenol orange is dissolved in water, and the solution is mixed with o-phenanthroline dissolved in alcohol or mixed with powdery ascorbic acid. It can manufacture by adding and mixing.

Next, the second chemical liquid will be described. The pH adjuster contained in the second chemical liquid is used to adjust the sample water to an acidic region where the metal indicator is sensitively discolored. As said pH adjuster, the buffer which consists of an acid or an acid and its salt is used normally. Acids usable here are inorganic acids such as nitric acid, hydrochloric acid and sulfuric acid, and organic acids such as acetic acid. In addition, salts of acids usable here are alkali metal salts such as nitric acid, hydrochloric acid, sulfuric acid and acetic acid. The acid or salt of an acid can use two or more types together.

Content of the said pH adjuster in a said 2nd chemical | medical agent is not specifically limited, since it operates so that pH of the sample water after addition may become a predetermined range, when adding the said 2nd chemical | medical solution to sample water, as mentioned later. . Usually, it is preferable that it is content which does not correspond to a foreign material from a viewpoint of ensuring the safety of handling. In the case where the water treatment agent contains an alkali metal hydroxide, since the sample water is an alkaline region, it is preferable to contain an acid in an amount that can be adjusted to a neutralization and acidic region as the pH adjuster.

The second chemical liquid may contain the masking agent in order to seal the first iron ions and copper ions in the sample water. The masking agent is usually contained in either of the first chemical liquid and the second chemical liquid. Content of the said masking agent in a said 2nd chemical liquid is not specifically limited because it operates so that a predetermined amount of said masking agent may be supplied, when adding the said 2nd chemical liquid to sample water, as mentioned later. Usually, from a viewpoint of solubility and economy, it can set suitably in 0.5 to 5 weight%.

The said 2nd chemical liquid can be manufactured by dissolving the said pH adjuster and other additives (the said masking agent) uniformly in water or alcohol which is a solvent. For example, the second chemical liquid for which EDTA is the quantitative object can be produced by dissolving nitric acid in water and adding and mixing o-phenanthroline dissolved in alcohol to this solution.

Next, the third chemical liquid will be described. The metal salt contained in the third chemical liquid is used to supply the specific metal ion to the sample water to which the first chemical liquid and the second chemical liquid are added. The metal salt is selected from an inorganic salt of a polyvalent metal capable of supplying the specific metal ion capable of changing the metal indicator to a predetermined color after first forming a complex with the chelating agent. As an inorganic salt of such a polyvalent metal, bismuth nitrate can be used, for example, when the said metal indicator is xylenol orange. Here, although the sample number to which xylenol orange was added is yellow at pH 6 or less, since xylenol orange becomes red when it complexes with bismuth ion, the end point of a proper operation is determined based on this color change. do. In addition, when o-phenanthroline (that is, the masking agent) which sealed ferrous ion and copper ion coexists in sample water, although the sample number is not yellow but orange, xylenol orange is bismuth ion. When it is complexed with red color, it turns red. Based on this color change, the end point of a proper operation is determined.

Content of the said metal salt in a said 3rd chemical liquid is set according to the resolution of the quantitative value of the said chelating agent. That is, the content of the metal salt is adjusted in advance so that the metal salt contained in one drop of the second chemical liquid discharged from the nozzle or the dropper reacts with a predetermined amount of the chelating agent. For example, under the conditions that the number of samples is 10 milliliters and one drop of the third chemical liquid discharged from the nozzle or the dropper is 0.035 g, EDTA in the free state and the complex state contained in the sample water is EDTA. When quantifying with resolution of 0.05 mg per drop as -2Na, the content of bismuth nitrate is set to 0.168% by weight.

In addition, the third chemical liquid may contain a surface tension reducing agent in order to make the discharge per one drop of the nozzle or the dropper constant. For example, when the bottle trunk of the dropping bottle with a nozzle is pressed slowly and when it is pressed quickly, the discharge of the said 3rd chemical liquid increases more when it presses slowly. On the other hand, when the third chemical liquid contains the surface tension reducing agent, the surface tension at the distal end of the nozzle can be lowered and the discharge per drop can be made constant. Here, the surface tension reducing agent is selected from substances which have a function of lowering the surface tension of the aqueous solution and do not react with the metal salt. As such a substance, an alcohol compound and a nonionic surfactant can be used. Examples of preferred alcohol compounds include glycols such as ethylene glycol and propylene glycol. In addition, examples of the preferable nonionic surfactants include polyoxyethylene alkyl ethers and polyalkylene alkyl ethers.

It is preferable to set content of the said surface tension decreasing agent in a said 3rd chemical liquid in the range of 20-40 weight% from a viewpoint of suppressing the fluctuation | variation of the discharge per droplet to +/- 5% or less.

The said 3rd chemical liquid can be manufactured by dissolving the said metal salt and other additives (the said surface tension lowering agent) uniformly in water or a lean acid which is a solvent. For example, the third chemical liquid for which EDTA is to be quantified can be produced by dissolving bismuth nitrate in dilute nitric acid and dissolving propylene glycol or the like as necessary.

The measuring kit may be configured to include a fourth container containing the powder reducing agent together with the first container, the second container, and the third container without containing the reducing agent in the first chemical liquid. It may be. Depending on the type of the reducing agent, when stored in an aqueous solution, there is a property that is susceptible to oxidation over time, for example, can withstand short-term storage for 1 to 3 months, but withstand long-term storage for 1 year. There may not be. When using the said reducing agent of such a property, long-term storage is attained by storing in the said 4th container as powder form.

The fourth container can be used without particular limitation as long as it is a container of a type capable of preventing air oxidation by a sealing stopper. Moreover, it is preferable that the capacity | capacitance of the said 4th container is set in the range of 25-100 milliliter from a viewpoint of the ease of handling and the ease of carrying. Moreover, it is more preferable that a measuring spoon is attached to the said 4th container. When the measuring spoon is attached, since a fixed amount of the reducing agent can be measured, the measuring spoon can be added to the sample water, thereby improving operability.

Next, the measuring method of the said chelating agent using the said measuring kit is demonstrated. First, a part of the water stored in the inside of the hot air is taken as sample water. This sample water collects a part of boiler water by a blower, when the said air conditioner is a boiler. In addition, this sample water collect | collects a part of circulating water with a spreading apparatus etc., when the said air conditioner is a cooling tower. Here, when the collected sample number exceeds 40 degreeC, it is preferable to cool a sample water to 40 degrees C or less from a viewpoint of ensuring the safety in proper operation. In addition, when the sample number collected has turbidity, it is preferable to filter the sample number from the viewpoint of accurately identifying the color change of the sample number in the proper operation. In order to provide a titration operation, the sample number collected collects predetermined amount (for example, 10-50 milliliters) with a measuring cylinder beforehand, and transfers it to the beaker.

Subsequently, the first chemical liquid is added to the collected sample water and mixed uniformly. The addition amount of the said 1st chemical liquid normally controls the dripping number from the said 1st container so that 0.0001-0.003 weight part of said metal indicators and 0.001-0.5 weight part of said reducing agents may respectively be added with respect to 100 weight part of samples. In addition, the second chemical liquid is added to the sample water and mixed uniformly. The addition amount of the said 2nd chemical liquid is normally added with the said pH adjuster in the quantity which becomes pH 6 or less, More preferably, the pH 1-3 which is hard to be influenced by divalent metal ions or rare earth metal ions. Adjust the dripping number from the second container so as to. When the first chemical liquid or the second chemical liquid contains the masking agent, the dropping number from the first container or the second container is adjusted so that 0.005 to 0.5 parts by weight of the masking agent is added. The order of addition of the first chemical liquid and the second chemical liquid is not particularly limited, and both may be added at the same time.

Here, when the addition amount of the said metal indicator is less than 0.0001 weight part, the coloring of a sample water is thin and it becomes difficult to distinguish the color change in the vicinity of the end point of a titration operation. On the other hand, when the addition amount of the metal indicator is more than 0.003 parts by weight, the number of samples is dark, and it becomes difficult to identify the color change near the end point of the proper operation. Moreover, when the addition amount of the said reducing agent is less than 0.001 weight part, there exists a possibility that it may become impossible to reduce all the ferric ion contained in sample water. On the other hand, when the addition amount of the reducing agent exceeds 0.5 parts by weight, since the excess of the reducing agent does not contribute to the reduction of the ferric ions, there is a fear that it is not economical. In addition, when the pH of the sample water exceeds 6, there is a fear that the metal indicator does not exhibit a predetermined color. Moreover, when the addition amount of the said masking agent is less than 0.005 weight part, all the ferric ion and copper ion contained in a sample water cannot be sealed, and there exists a possibility that an accurate quantitative value may not be obtained. On the other hand, when the addition amount of the said masking agent exceeds 0.5 weight part, since the said excess masking agent does not contribute to sealing of ferrous ion and copper ion, there exists a possibility that it may become uneconomical.

In the step of adding the first chemical liquid, when the first chemical liquid is configured not to contain the reducing agent, it is usually powdered from the fourth container into the sample water immediately before adding the first chemical liquid. The reducing agent is added and mixed uniformly. At this time, the amount of the reducing agent added is controlled so as to be 0.001 to 0.5 parts by weight based on 100 parts by weight of the sample, similarly to the case where the first chemical is contained in the reducing agent.

When the first chemical liquid containing the reducing agent is added to the sample water, or when the powder-like reducing agent is added, the ferric ions in the sample water are reduced to ferrous ions. And this ferrous ion forms a complex preferentially with the said masking agent. For this reason, the said metal indicator, for example, xylenol orange, is prevented from forming a complex with ferric ions and discoloring, thereby ensuring the normal color of the sample water.

Next, the third chemical liquid is added dropwise from the third container to the sample water to which the first chemical liquid and the second chemical liquid are added, and the number of droppings until the sample water discolors is counted. At this time, the third chemical liquid is added dropwise while shaking the beaker so that the sample water and the third chemical liquid are uniformly mixed.

When the third chemical liquid is added dropwise to the sample water to which the first chemical liquid and the second chemical liquid are added, the chelating agent preferentially forms a complex with the specific metal ion. When the entire amount of the chelating agent forms a complex with the specific metal ion, the metal indicator forms a complex with an excess of the specific metal ion and the number of samples discolors. For example, when the chelating agent is EDTA and its alkali metal salt, when the third chemical is added dropwise to the sample water to which the first and second chemicals are added, EDTA preferentially forms a complex with bismuth ions. do. When the total amount of EDTA forms a complex with bismuth ions, xylenol orange forms a complex with an excess of bismuth ions, and when the sample number is yellow (o-phenanthrol combined with ferrous ions coexists, Orange color).

In addition, when the said 3rd chemical liquid is dripped in presence of the said masking agent, the 1st iron ion and copper ion complexed with the said chelating agent will form a complex preferentially with the said masking agent. For this reason, the reaction time until the whole quantity of the said chelating agent forms a complex with the said specific metal ion quickly, and a sample water discolors is shortened.

Next, the concentration of the chelating agent in the sample water is specified based on the drop number of the third chemical liquid required to the end point of the titration operation. As described above, the third chemical liquid is prepared such that the metal salt contained in one drop reacts with a predetermined amount of the chelating agent, and therefore, the equivalent amount of the chelating agent per one drop of the third chemical liquid, the third chemical liquid. From the dropping number and the aliquot of the sample water, the concentration of the chelating agent in the sample water can be calculated.

By the way, in the said hot air machine, the said chelating agent is melt | dissolving in water in the state which formed the complex state, such as a glass state or hardness powder. The water stored in the inside of the hot air is usually blown to the outside intermittently so as to maintain a predetermined concentration ratio. Or since replenishment water is regularly supplied, there is no possibility that the chelating agent crystallizes in water beyond the solubility or precipitates on the heat transfer surface. For this reason, the concentration of the chelating agent in the hot air correlates with the concentration of the water treatment agent, and the concentration of the water treatment agent is easily specified from the concentration of the chelating agent and the blending ratio of the chelating agent in the water treatment agent. Therefore, it is possible to judge whether or not the supply amount of the water treatment agent is appropriate based on this water treatment agent concentration.

As described above, according to the embodiment of the present invention, the concentration of the water treatment agent can be easily known at the site where the hot air is installed. As a result, it is possible to judge on the spot whether the water treatment agent supply amount to the hot air is appropriate on the spot, and the maintenance management regarding the water treatment can be improved.

Example

(Preparation of First Chemical Solution)

Using xylenol orange as a metal indicator, o-phenanthroline as a masking agent, distilled water and ethanol as a solvent, these components were mixed in the content shown in Table 1, and the 1st chemical liquid was prepared. After preparation, this first chemical liquid was filled into a polyethylene dropping bottle (capacity 100 milliliters, hereinafter referred to as "first container") made of polyethylene. The dripping amount per 1 drop of the said 1st chemical liquid using the said 1st container was 0.035g (average value).

TABLE 1

ingredient Content (% by weight) Xylenol Orange 0.3 o-phenanthrol 2 Distilled water 77.7 ethanol 20

(Preparation of the second chemical)

It was set as the 2nd chemical liquid using 10% aqueous nitric acid solution as a pH adjuster. The second chemical liquid was filled into a polyethylene dropping bottle (capacity 100 milliliters, hereinafter referred to as a "second container") made of polyethylene. The dripping amount per 1 drop of the said 2nd chemical liquid using the said 2nd container was 0.035g (average value).

(Preparation of Third Chemical Solution)

Bismuth nitrate pentahydrate was used as a metal salt, and 0.5 mol / liter nitric acid aqueous solution was used as a solvent, and each of these components was mixed by content shown in Table 2, and the 3rd chemical liquid was prepared. After the preparation, the third chemical liquid was filled into a polyethylene dropping bottle (capacity 100 milliliters, hereinafter referred to as "third container") made of polyethylene. The dripping amount per 1 drop of the said 3rd chemical liquid using the said 3rd container is 0.035g (average value), and 1 drop of the said 3rd chemical liquid is equivalent to 0.05 mg of EDTA-2Na.

Table 2

ingredient Content (% by weight) Bismuth Nitrate Pentahydrate 0.21 0.5 mol / liter nitric acid solution 99.79

(Collection of sample water)

In a perfusion boiler supplied with a water treatment agent containing ethylenediamine tetrasodium acetate (EDTA-2Na) as a scale inhibitor, 67 units were randomly extracted from all over the country, and sample water was collected from a continuous blower during operation. . In the water treatment agent, an alkali metal hydroxide was blended with EDTA-2Na as a corrosion inhibitor, and the pH of the sample water collected was in the range of 10.5 to 12. After cooling each sample water to room temperature, 10 milliliters were each fractionated to the beaker using the measuring cylinder, and the 67 aliquots of the 1st aliquot sample water were prepared. From each sample water, 5 milliliters were each fractionated into a beaker using a measuring cylinder to prepare a second sample water of 67 samples.

(Measurement of EDTA by simple titration method)

20 mg of powdery ascorbic acid was added to the first aliquot of the sample water as a reducing agent, and uniformly dissolved. The first aliquot sample water to which the reducing agent was added was tested by adding one drop of the first chemical liquid from the first container, and then adding five drops of the second chemical liquid from the second container to uniformly mix the same. A number was written. Next, the third chemical liquid was dropped into the test water from the third container, and the drop number until the test water changed from orange to red was counted. The concentration of EDTA-2Na in the sample water was calculated from the equivalent amount of EDTA-2Na per drop of the third chemical solution, the dropping number of the third chemical solution and the aliquots of the sample water. In the above operation, the time required for the measurement per sample was 1-3 minutes.

(Measurement of EDTA by High-Speed Liquid Chromatography)

In order to compare with the quantitative value of EDTA by the simple titration method, EDTA was measured by the high performance liquid chromatography method (HPLC method) about the 2nd aliquot sample water. First, commercially available 0.01 mol / liter ethylenediamine dibasic tetrasodium acetate (EDTA-2Na) aqueous solution was diluted with distilled water, and 0 mg / liter, 10 mg / liter, 20 mg / liter, 40 mg / liter and 80 mg / liter standard solution. Were prepared respectively. Further, 0.27 g of ferric chloride hexahydrate was dissolved in 0.01 N hydrochloric acid, and the total amount thereof was set to 100 milliliters to prepare 0.01 mol / liter of ferric chloride solution.

5 milliliters of 0.01 mol / liter of ferric chloride solution was respectively added to 5 milliliters of each standard solution, filtered through a 0.2 µm membrane filter, and 10 microliters of each solution were subjected to high performance liquid chromatography. And the calibration curve was created from each obtained peak height and density | concentration. Here, the conditions of high performance liquid chromatography are as follows.

-Column size: inner diameter 4.6mm, length 150mm

-Fixed phase: Chemical modification of octadecyl group on all porous silica gel

-Mobile phase: adjusted to pH3.0 by adding acetic acid to 0.01 mol / liter of tetra-n-butylammonium hydroxide solution

Mobile phase flow rate: 1.0 milliliter / minute

Selective wavelength of detector: 255nm

Next, 5 milliliters of 0.01 mol / liter of ferric chloride solution was added to the second aliquot, followed by filtration through a 0.2 μm membrane filter, and then a high-speed liquid under the same conditions as the standard solution for 10 microliters of each solution. Chromatography was performed and the peak height was measured. The concentration of EDTA-2Na in the sample water was calculated based on the calibration curve prepared in advance. In the above operation, the time required for the measurement per sample was 25 minutes.

(evaluation)

About each sample number, the graph which plotted the quantitative value by the simple titration method with respect to the quantitative value by the HPLC method is shown in FIG. According to FIG. 1, the difference of about 5 mg / liter may generate | occur | produce on the positive side with respect to the quantitative value by the simple titration method on the positive side with respect to the quantitative value of HPLC method. This is because the resolution of the quantitative value in the simple titration method is set to 5 mg / liter. The quantitative value of the simple titration method shows a nearly linear correlation with the quantitative value of the HPLC method, and it can be seen that the reliability is high. In addition, the simple titration method is effective for measurement in the field because the measurement can be performed in a short time without using a special apparatus.

According to this invention, the concentration of the water treatment agent can be easily known at the site where the hot air heater is installed. As a result, it is possible to judge on the spot whether the water treatment agent supply amount to the hot air is suitably on the spot, and it is possible to improve the maintenance of the water treatment.

Claims (10)

As a measuring method of the chelating agent concentration which simultaneously measures the concentration of ethylenediamine tetraacetic acid in the free state and the complex salt state contained in the water in a hot air machine, Collecting the sample water from the hot air machine, Adding ascorbic acid to the sampled sample water as a reducing agent, Adding a first chemical liquid containing xylenol orange as a metal indicator and o-phenanthrolin as a masking agent to the sample water to which the reducing agent is added; Adding a second chemical liquid containing nitric acid to the sample water to which the reducing agent and the first chemical liquid are added, adjusting the pH to 6 or less, and producing a target water; Dropping a third chemical liquid containing bismuth nitrate as a metal salt for discoloring the metal indicator, and counting the number of drops until the target water discolors; A method for measuring a chelating agent, comprising the step of specifying the concentration of ethylenediamine tetraacetic acid in the free state and the complex salt state in the sample water based on the drop number of the third chemical liquid. delete delete delete delete delete A chelating agent measuring kit for simultaneously measuring the concentration of ethylenediamine tetraacetic acid in free and complex salts contained in water in a hot air machine, A first container in which a first chemical liquid containing xylenol orange as a metal indicator and o-phenanthrolin as a masking agent is contained; a second container containing a second chemical liquid containing nitric acid as a pH adjusting agent, A third container containing a third chemical liquid containing bismuth nitrate as a metal salt for discoloring the metal indicator, A kit for measuring a chelating agent, comprising a fourth container containing ascorbic acid as a reducing agent. delete delete delete

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