JP2012011287A - Measurement method and automatic measurement apparatus of aluminum concentration in test water, and control method of silica-based scale adhesion inhibitor concentration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for efficiently measuring concentration of aluminum being a factor which causes silica-based scale adhesion occurring on cooling water system, a boiler water, a membrane processing and a reduction well of geothermal power plant or the like, in situ.SOLUTION: There is provided the method (1) for measuring the concentration of aluminum being a factor which causes silica-based scale in test water. In the method, a reaction reagent comprising a combination of 7-iodine-8-hydroxyquinoline-5-sulfonic acid and a buffer solution is added to the test water and, thereafter, the aluminum concentration is obtained from the absorbance measured at a wavelength of aluminum analysis. There is also provided the automatic measurement apparatus (2) of aluminum concentration in the test water and the control method (3) of silica-based scale adhesion inhibitor concentration.

Description

  The present invention relates to an aluminum concentration measurement method, preferably an automatic measurement method, and aluminum for measuring the aluminum concentration in the field in water systems such as cooling water systems and boiler water systems, which cause silica-based scales in the water to be treated. The present invention relates to an automatic concentration measuring device and a method for controlling the concentration of a silica-based scale adhesion inhibitor added to the water to be treated based on the measured aluminum concentration.

  In cooling water systems, boiler water systems, membrane treatment, and reduction wells of geothermal power plants, scale obstacles occur on heat transfer surfaces, piping, and membrane surfaces that come into contact with water. From the standpoint of resource saving and energy saving, when highly concentrated operation is performed (in the case of membrane treatment, when the recovery rate is increased), the dissolved salts are concentrated to form a sparingly soluble salt. The scale generated in the heat exchange section inhibits heat transfer, the adhesion to the piping reduces the flow rate, the adhesion to the membrane causes the flux to decrease, and the generated scale peels off and circulates in the system, pumping, piping, heat exchange Cause blockage of parts, and the promotion of scaling in piping and heat exchange parts associated with blockage. It is also known that the same phenomenon occurs in the reduction well of a geothermal power plant.

Examples of the scale species to be generated include calcium carbonate, calcium sulfate, calcium sulfite, calcium phosphate, calcium silicate, magnesium silicate, magnesium hydroxide, zinc phosphate, zinc hydroxide, and basic zinc carbonate.
Conventionally, for calcium-based scales, carboxyl groups such as maleic acid, acrylic acid, and itaconic acid are effective, and if necessary, vinyl sulfonic acid, allyl sulfonic acid, 3-allyloxy-2-hydroxypropane sulfonic acid, etc. In general, a copolymer obtained by combining a vinyl monomer having a sulfonic acid group with a nonionic vinyl monomer such as acrylamide according to the water quality of interest is used. Further, inorganic polyphosphoric acids such as sodium hexametaphosphate and sodium tripolyphosphate, and phosphonic acids such as hydroxyethylidene diphosphonic acid and phosphonobutanetricarboxylic acid are generally used.

On the other hand, as a silica-based scale inhibitor, polyacrylamide (for example, see Patent Document 1), polyethylene glycol (for example, see Patent Document 2), polyvinylformamide (PNVF) (for example, see Patent Document 3) acrylic acid, acrylamide methyl Propanesulfonic acid, substituted acrylamide terpolymers (see, for example, Patent Document 4), polyvinylpyrrolidone (see, for example, Patent Document 5), and the like have been proposed.
However, although the acrylamide polymer is effective when the silicic acid concentration in water is low, the effect is poor when the silicic acid concentration is high. Polyethylene glycol has an anti-scale adhesion effect when the silicic acid concentration is low, but the effect is not stable because it is easily affected by other coexisting ions. Polyvinyl formamide has a cationic composition, A thing with a high ratio tends to be adsorbed by the metal which comprises water systems, such as piping. Terpolymers of acrylic acid, acrylamidomethylpropane sulfonic acid, and substituted acrylamide are effective for silica-based scales produced at high temperatures, but not sufficiently effective for silica-based scales produced at low temperatures. In particular, it was difficult to prevent scales adhering to the low temperature part.

Further, a copolymer of acrylic acid / sulfonic acid / N-vinylcarboxylic acid amide has been proposed for silica-based scales produced in the low temperature part with aluminum involved (see, for example, Patent Document 6).
As described above, various agents have been proposed as silica-based scale inhibitors, but since the coexisting substances such as magnesium and aluminum are involved in the formation of the silica-based scale, the agents corresponding to the coexisting substances affecting each aqueous system. Need to apply. However, the present condition is that it is not performed in advance to investigate the coexisting substances involved in the generation of the silica-based scale in advance.

  Recently, aluminum has been reported as one of the coexisting substances involved in the formation of silica-based scale, and positively charged aluminum that interacts with negatively charged silica electrostatically in the cooling water system is a binder for silica-based scale formation. It has been reported (see, for example, Non-Patent Document 1). However, in that report, positively charged aluminum is identified by fractionation using filter paper with different pore sizes and measurement by zeta potential, and it should be applied as a method for monitoring the aluminum concentration involved in silica-based scale formation in aqueous systems. It is difficult.

JP 61-107998 A JP-A-2-31894 Japanese Patent Laid-Open No. 11-57883 Japanese Patent No. 3055815 Japanese Patent No. 4048580 JP 2008-36562 A

Journal of Colloid and Interface Science 335, 18-23 (2009)

  The present invention has been made under such circumstances, and the concentration of aluminum that causes silica-based scale adhesion that occurs in cooling water systems, boiler water, membrane treatment, reduction wells of geothermal power plants, etc. is efficiently reduced locally. It is an object of the present invention to provide a method for measuring, a device for the same, and a method for controlling the concentration of the silica-based scale adhesion inhibitor added to the water to be treated based on the measured aluminum concentration.

As a result of intensive studies to achieve the above object, the present inventors have obtained the following knowledge.
Aluminum that causes generation of the silica-based scale has a positive charge, and the silica-based scale is generated by electrostatic interaction with the negatively-charged silica. The aluminum having a positive charge is 7-iodo-8. Focusing on the fact that it reacts instantaneously with -hydroxyquinoline-5-sulfonic acid, further research is conducted, and a reaction reagent comprising a combination of 7-iodo-8-hydroxyquinoline-5-sulfonic acid and a buffer is sampled. It was found that the aluminum concentration can be obtained by measuring the absorbance at a wavelength at which aluminum exhibits absorption after the addition. The present invention has been completed based on such findings.

That is, the present invention provides the above (1) to (10).
(1) A method for measuring the concentration of aluminum that causes silica-based scale in test water, wherein a reaction reagent comprising a combination of 7-iodo-8-hydroxyquinoline-5-sulfonic acid and a buffer solution is tested. A method for measuring aluminum concentration in test water, wherein the aluminum concentration is determined from the absorbance measured at the aluminum analysis wavelength after being added to water.
(2) After adding the reaction reagent to the test water, the absorbance is measured at the aluminum analysis wavelength and the iron analysis wavelength, respectively, and the iron concentration is determined from the absorbance at the iron analysis wavelength, and the iron contribution at the aluminum analysis wavelength is based on this iron concentration. The method for measuring an aluminum concentration in test water according to claim 1, wherein the absorbance of water is obtained and the aluminum concentration is obtained from the absorbance obtained by removing the absorbance of the iron contribution from the absorbance at the aluminum analysis wavelength.
(3) The method for measuring the aluminum concentration in the test water according to (1) or (2), wherein the absorbance is measured within 1 minute after the addition of the reaction reagent.
(4) Measure the change in absorbance with time after addition of the reaction reagent, calculate the aluminum concentration at each time, and calculate the obtained aluminum concentration at 0 minutes by nonlinear analysis of the change in the obtained aluminum concentration over time. The method for measuring aluminum concentration in test water according to (1) or (2) above.
(5) A method for automatically measuring the concentration of aluminum that causes a silica-based scale in test water, the step of continuously passing the test water through an optical measurement unit, 7-iodo-8-hydroxyquinoline-5-sulfone A step of adding a reaction reagent comprising a combination of an acid and a buffer solution to the test water to form a measurement sample solution, and the aluminum concentration in the measurement sample solution is automatically measured in the optical measurement unit And a method for automatically measuring the aluminum concentration in the test water.
(6) The method for automatically measuring the aluminum concentration in the test water of (5) above, wherein the absorbance is measured within 1 minute after the addition of the reaction reagent.
(7) Measure the change in absorbance over time after addition of the reaction reagent, calculate the aluminum concentration at each time, and calculate the obtained aluminum concentration at 0 minutes by nonlinear analysis of the change over time in the obtained aluminum concentration. The method for automatically measuring aluminum concentration in test water according to (5) above.
(8) The above (5), comprising means for mixing the prediluted reaction reagent solution and test water so that the aluminum concentration in the measurement sample water is within a quantitative range in which the calibration curve for optical measurement shows linearity. ) Automatic method for measuring aluminum concentration in test water.
(9) A device for automatically measuring the concentration of aluminum that causes silica-based scale in the test water, and means for continuously passing the test water through the optical measurement unit, 7-iodo-8-hydroxyquinoline-5-sulfone A means for forming a measurement sample solution by adding a reaction reagent comprising a combination of an acid and a buffer solution to the test water, and automatically measuring the aluminum concentration in the measurement sample solution in the optical measurement unit A device for automatically measuring the aluminum concentration in the test water.
(10) The test water obtained by the method for measuring aluminum concentration in the test water of any one of (1) to (4) or the method for automatically measuring the aluminum concentration in the test water of any of (5) to (8) Silica scale anti-sticking agent concentration, characterized by controlling the amount of silica-based scale anti-sticking agent added to the water to be treated of the sample water source based on the concentration measurement data of aluminum that causes silica scale Control method.

  According to the present invention, in a cooling water system, a boiler water system, or the like, a method for measuring the concentration of aluminum that causes a silica-based scale in water to be treated, preferably an automatic measuring method, and aluminum for measuring the aluminum concentration on site An automatic concentration measuring device and a method for controlling the concentration of the silica-based scale adhesion inhibitor added to the water to be treated can be provided based on the measured aluminum concentration.

It is a flowchart of an example of the aluminum concentration automatic measurement apparatus in the test water in this invention. It is a graph which shows the absorbance change [(a)] and Al concentration change [(b)] by elapsed time in Example 3, respectively. In Example 5, the absorbance change [(a)] at a wavelength of 370 nm and the absorbance change [(b)] at a wavelength of 600 nm, and the absorbance analysis result [(c)] and Al concentration calculation [(d)] in Example 5 are shown. It is a graph to show. 6 is a graph showing the correlation between Example 1, Example 3 and Comparative Example 1. It is a device schematic diagram of a simulated cooling water system with a retained water amount of 100 L having a heat exchanger. It is a graph which shows the result controlled using the automatic measurement apparatus of Al concentration.

First, the method for measuring the aluminum concentration in the test water of the present invention will be described.
[Measurement method of aluminum concentration in test water]
The method of measuring the aluminum concentration in the test water, particularly the water to be treated or the supply water (make-up water) of the water to be treated (hereinafter sometimes simply referred to as “Al concentration measuring method”) is a silica-based scale in the test water. This is a method for measuring the concentration of aluminum as a factor, and after a reaction reagent comprising a combination of 7-iodo-8-hydroxyquinoline-5-sulfonic acid and a buffer solution is added to the test water, aluminum shows absorption. The aluminum concentration is obtained from the absorbance measured at the wavelength (aluminum analysis wavelength).

(Preparation of sample solution for absorbance measurement)
In the Al concentration measurement method, a reaction reagent composed of a combination of 7-iodo-8-hydroxyquinoline-5-sulfonic acid and a buffer solution is added to test water to prepare a sample solution for absorbance measurement.
Regarding the specific method for preparing the sample solution for absorbance measurement, the specifications when the total volume is made up to 10 mL are shown below. When changing the volume to be measured up, if the amount of reagent or sample water is used in proportion, Good.

<Reaction reagent>
In the Al concentration measurement method, as a reaction reagent, 7-iodo-8-hydroxyquinoline-5-sulfonic acid and a buffer solution, preferably a buffer solution of pH 4.5 to 5.5, for example, an acetate buffer solution of pH 5 Use a combination of
7-iodo-8-hydroxyquinoline-5-sulfonic acid is usually used in the form of an aqueous solution having a concentration of 1 to 5 mmol / L, and the amount thereof is an aqueous solution having a concentration of 2.5 mmol / L per 1 mL of test water, and usually 1 mL. Above, preferably 1 mL.
On the other hand, a buffer solution having a pH of 4.5 to 5.5, for example, an acetic acid buffer solution having a pH of 5, is a mixture of acetic acid and an acetate salt (Na salt, K salt, ammonium salt, etc.) having a molar ratio of about 1: 2. It is used in the form of an aqueous solution containing at a concentration of about 1 to 1 mol / L. The amount is usually 1 mL or more, preferably 2 mL, with an acetic acid buffer solution having a concentration of 1 mol / L per 1 mL of test water.

The sample solution for absorbance measurement is prepared by adding a 7-iodo-8-hydroxyquinoline-5-sulfonic acid aqueous solution and a buffer solution to a container with a lid capable of measuring a certain volume, such as a measuring flask, a colorimetric tube, a lid with a measuring cell. Can be prepared by adding a predetermined amount of each and then adding 1 to 8 mL of test water to make the whole amount constant.
In the present invention, a solution prepared by previously mixing a 7-iodo-8-hydroxyquinoline-5-sulfonic acid aqueous solution and a buffer solution at a predetermined ratio may be used as a reaction reagent.

(Calculation of aluminum concentration by absorbance measurement)
In the Al concentration measurement method, the absorbance at the wavelength at which aluminum absorbs (aluminum analysis wavelength) and the wavelength at which iron absorbs (iron analysis wavelength) is measured for the sample solution for absorbance measurement prepared as described above. Then, the aluminum concentration is calculated from these absorbance values. The procedure is shown below.
First, a reaction reagent is added to pure water, and the obtained aqueous solution is put into a measurement cell, and a wavelength at which aluminum absorbs (aluminum analysis wavelength), specifically 350 to 400 nm, preferably 370 nm and iron absorbs. The indicated wavelength (iron analysis wavelength), specifically, the absorbance at 500 to 700 nm, preferably 600 nm, is measured, respectively, and zero correction is performed. Next, the sample solution for absorbance measurement is put into a measurement cell, and the absorbance at the aluminum analysis wavelength and the iron analysis wavelength is measured. At this time, the absorbance measurement sample solution is measured immediately after the preparation, preferably within 1 minute, or the change in absorbance with time is measured.
Regarding the iron analysis wavelength, the absorbance at a wavelength of 400 to 600 nm, preferably 450 nm, can be used instead of the absorbance at a wavelength of 500 to 700 nm, preferably 600 nm.

(1) When calculating the Al concentration by analyzing based on the absorbance measured within 1 minute, three calibration curves prepared in advance, that is, the Al calibration curve at the aluminum analysis wavelength, the iron analysis wavelength The Al concentration in the sample solution is calculated by the following procedure from the Fe calibration curve and the Fe calibration curve at the aluminum analysis wavelength.
Fe concentration: The Fe concentration in the sample solution is calculated from the absorbance measured at the iron analysis wavelength and the Fe calibration curve at the iron analysis wavelength.
Al concentration: From the Fe concentration calculated above and the Fe calibration curve at the aluminum analysis wavelength, the absorbance indicated by Fe at the aluminum analysis wavelength is calculated.
The absorbance derived from Al is determined by subtracting the absorbance indicated by Fe from the absorbance measured at the aluminum analysis wavelength. The Al concentration in the sample solution is calculated from the absorbance derived from Al and the calibration curve of Al at the aluminum analysis wavelength.
(2) On the other hand, when calculating the Al concentration at time zero based on the above-mentioned change in absorbance over time, each measurement time is measured in the same procedure as in the above (1) from the previously prepared calibration curves for Al and Fe. The Al concentration at is calculated. A non-linear analysis is performed on the calculated change in Al concentration over time based on the following equation to calculate the Al concentration (Al ₀ ) at time zero.
Al ₀ + Al ₁ + Al ₂ = Al ₀ + Al ₁ (1- ^{et / t1} ) + Al ₂ (1- ^{et / t2} )

[Aluminum concentration automatic measurement method in test water]
The present invention is also a method for automatically measuring the concentration of aluminum that causes silica scale in test water, the step of continuously passing the test water through an optical measuring unit, 7-iodo-8-hydroxyquinoline-5 A step of forming a measurement sample solution by adding a reaction reagent comprising a combination of a sulfonic acid and a buffer solution to the sample water, and automatically measuring the aluminum concentration in the measurement sample solution in the optical measurement unit And a method for automatically measuring the aluminum concentration in the test water.
The calculation of the aluminum concentration by the absorbance measurement in this Al concentration automatic measurement method is as described above.
Further, in this Al concentration automatic measurement method, the reaction reagent solution and test water diluted in advance are used so that the Al concentration in the measurement sample solution falls within the quantitative range in which the calibration curve for optical measurement shows linearity. It is desirable to have a means for mixing.

[Al concentration automatic measuring device]
The apparatus for automatically measuring aluminum concentration in test water of the present invention (hereinafter sometimes simply referred to as “Al concentration automatic measuring apparatus”) is an apparatus for automatically measuring the concentration of aluminum that causes a silica-based scale in test water. A reaction reagent comprising a combination of 7-iodo-8-hydroxyquinoline-5-sulfonic acid and a buffer, which is a means for continuously passing the test water through the optical measurement unit, is added to the test water. It comprises at least means for forming a measurement sample solution and means for automatically measuring the aluminum concentration in the measurement sample solution in the optical measurement unit.
The Al concentration automatic measuring apparatus of the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 is a flow chart of an example of an Al concentration automatic measuring apparatus according to the present invention.
The flow rate is adjusted by the flow rate adjusting valve 2 from the water channel 1 of the target water, and the sample water is taken in. When sample water is taken in only at the time of measurement, the flow adjustment valve 2 may be released at the start of measurement and closed at the end of measurement. Further, when sample water is taken in only at the time of measurement using a metering pump (not shown), the metering pump can be operated at the start of measurement and stopped at the end of the measurement.
The sample water taken in is removed from the contaminant particles mixed by the strainer 3 and then passed to the subsequent automatic measuring device concentration measuring device 4 according to the present invention. The strainer 3 is not essential.

The automatic measuring device 4 includes a sample water supply channel 401 that is connected to the strainer 3 first. In this sample water supply channel 401 (hereinafter referred to as “supply channel”), a reaction reagent tank in which a reaction reagent R having a property of chemically reacting with aluminum contained in the sample water to produce a reaction product is stored. A reaction reagent injection path 403 (hereinafter referred to as “injection path”) connected to 402 is open. A plurality of reaction reagent tanks 402 and injection paths 403 for adding a reaction reagent to the sample water can be provided.
In the middle of the injection path 403, an injection pump P1 for adjusting the injection amount of the reaction reagent R is laid. The reaction reagent R is supplied to the supply path 401 while the addition amount is adjusted by the injection pump P1 during measurement. Injected. The addition amount of the reaction reagent R is determined according to the level of aluminum concentration in the sample water.

The reaction reagent R injected into the supply path 401 is mixed with the sample water flowing through the supply path 401 to become a measurement sample solution. The mixing method may be agitation by the action of the sample water flow, and an additional stirring site such as an orifice-like structure, a wing structure that forms a vortex, a static mixer, a line mixer, and a slater is provided. Also good.
Subsequently, the above-described measurement sample solution is introduced into the measurement cell 405 provided in the optical measurement interior 404 through the supply path 401, passes through the measurement cell 405, and is discharged from the discharge path 408. As the measuring means of the optical measuring unit 404, a well-known conventional optical measuring means for spectrophotometric analysis can be appropriately employed.
Here, since the present invention is suitable for on-stream monitoring of the aluminum concentration, the measurement cell 405 may be devised so that it can be automatically cleaned in order to enable continuous measurement over a long period of time. That is, a cleaning liquid injection device (not shown) is attached to the measurement cell 405 so that the cleaning liquid can be injected into the measurement cell 405 at regular intervals.

Reference numeral 406 denotes a light source for irradiating the measurement sample liquid in the measurement cell 405 with light, and reference numeral 407 detects the intensity of transmitted light of the light irradiated to the sample liquid in the measurement cell 405. Represents a light receiving unit that captures as an electrical signal, and reference numeral 409 represents an analysis unit connected to the light receiving unit 407.
Here, in the present invention, the aluminum concentration value obtained by the analysis unit 409 is converted into an electric signal and transmitted to the control unit 5 in which a CPU or the like is built, and the water treatment agent (scale prevention agent) is stored. The injection amount of the processing agent injection pump P2 provided in the middle of the processing agent addition path 7 connected to the water processing agent storage tank 6 can be automatically controlled.

[Method for controlling concentration of silica-based scale adhesion inhibitor]
The method for controlling the concentration of the silica-based scale adhesion inhibitor of the present invention is based on the aluminum concentration measurement data that causes the silica-based scale in the test water obtained by the Al concentration measuring method or the Al concentration automatic measuring method of the present invention described above. Based on this, the amount of the silica-based scale adhesion inhibitor added to the water to be treated of the test water source is controlled.

(Silica-based scale adhesion inhibitor)
Examples of the silica-based scale adhesion inhibitor added to the water to be treated of the test water source include inorganic polyphosphoric acids such as sodium tripolyphosphate and sodium hexametaphosphate; acrylic acid, maleic acid, maleic acid / acrylic acid, maleic acid / sulfone Examples thereof include copolymers having acid, acrylic acid / sulfonic acid and the like as monomer components; copolymers having acrylic acid / sulfonic acid / nonionic group-containing monomers and the like as monomer components. Further, if necessary, it can be further mixed with an anti-corrosive agent such as organic phosphonic acid and zinc chloride, a sterilizer such as hydrazine, Cl-MIT, hypochlorous acid and sulfamic acid, etc. in the same solution and added.
In addition, there is no restriction | limiting in particular in the water quality conditions and driving | running conditions in the case of applying this invention.

  Examples of the sulfonic acid include vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, isoprene sulfonic acid, 3-allyloxy-2-hydroxypropane sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and 2-methacrylic acid. Amido-2-methylpropanesulfonic acid, 4-sulfobutyl methacrylate, allyloxybenzenesulfonic acid, methallyloxybenzenesulfonic acid and their metal salts, etc., and as the nonionic group-containing monomer, for example, Alkylamide having 1 to 5 carbon atoms, acryloylmorpholine, N-vinylcarboxylic acid amides, hydroxyethyl (meth) acrylate, monopoly (meth) acrylate of (poly) ethylene oxide / propylene oxide having addition moles of 1 to 30 Mo 1-30 (poly) monovinyl ether of ethylene oxide / propylene oxide.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Example 1
Each solution prepared by using polyaluminum chloride and having an Al concentration of 4 mg / L as Al and sodium metasilicate so that the SiO ₂ concentration is 0, 25, 50 mg / L and pH 8.5 was used as sample water.
To a solution of 1 mL of 2.5 mmol / L 7-iodo-8-hydroxyquinoline-5-sulfonic acid (hereinafter abbreviated as “Ferron”) and 2 mL of 1 mol / L acetate buffer (pH 5.0) The absorbance at 370 nm of the solution added to 2 mL of sample water and made up to 10 mL was measured with a 10 mm cell within 1 minute after addition of the reaction reagent. Then, the Al concentration in the sample water was calculated from a calibration curve prepared in advance. The results are shown in Table 1.

Example 2
A solution prepared by using polyaluminum chloride and having an Al concentration of 4 mg / L as Al, sodium metasilicate so that the SiO ₂ concentration is 25 mg / L, and pH 8.5 was used as sample water.
To 3 mL of a reaction reagent (2.5 mmol / L 7-iodo-8-hydroxyquinoline-5-sulfonic acid: 1 mol / L acetate buffer (mixed at pH 5.0, volume ratio = 1: 2)) The absorbance at 370 nm of the solution made up to 10 mL was measured in a 10 mm cell within 1 minute after the addition of the reaction reagent, and the Al concentration in the sample water was calculated from a calibration curve prepared in advance. The results are shown in Table 1.

Example 3
Each solution prepared by using polyaluminum chloride and having an Al concentration of 4 mg / L as Al and sodium metasilicate so that the SiO ₂ concentration is 0, 25, 50 mg / L and pH 8.5 was used as sample water.
To 3 mL of a reaction reagent (1 mmol / L 7-iodo-8-hydroxyquinoline-5-sulfonic acid: 1 mol / L acetate buffer (mixed at pH 5.0, volume ratio = 1: 2)), 2 mL of sample water The time-dependent change in absorbance at 370 nm of the solution that was added and made up to 10 mL was measured with a 10 mm cell, and the Al concentration in the sample water at each time was calculated from a calibration curve prepared in advance, and the following formula was used. , Al ₀ was calculated and the results are shown in Table 1.
Al ₀ + Al ₁ + Al ₂ = Al ₀ + Al ₁ (1- ^{et / t1} ) + Al ₂ (1- ^{et / t2} )
FIG. 2 is a graph showing changes in absorbance [(a)] and changes in Al concentration [(b)] over time.

Example 4
Using polyaluminum chloride, the Al concentration is 4 mg / L as Al, using sodium metasilicate, the SiO ₂ concentration is 25 mg / L, and using iron chloride, the Fe concentration is 4 mg / L as Fe, and the pH is 8.5. The solution obtained was used as sample water.
To 3 mL of a reaction reagent (2.5 mmol / L 7-iodo-8-hydroxyquinoline-5-sulfonic acid: 1 mol / L acetate buffer (mixed at pH 5.0, volume ratio = 1: 2)) The absorbance at 370 nm and 600 nm of the solution made up to 10 mL was measured in a 10 mm cell within 1 minute after the addition of the reaction reagent, and from the previously prepared Fe calibration curve (600 nm), The Fe concentration was calculated.
From the calculated Fe concentration and a previously prepared Fe calibration curve (370 nm), the absorbance indicated by Fe at 370 nm was calculated. The absorbance indicated by Fe was subtracted from the absorbance measured at 370 nm to obtain absorbance derived from Al. The Al concentration in the sample water was determined from the Al calibration curve prepared in advance and the absorbance derived from Al. The results are shown in Table 1.

Example 5
Using polyaluminum chloride, the Al concentration is 4 mg / L as Al, using sodium metasilicate, the SiO ₂ concentration is 25 mg / L, and using iron chloride, the Fe concentration is 4 mg / L as Fe, and the pH is 8.5. The solution obtained was used as sample water.
To 3 mL of a reaction reagent (2.5 mmol / L 7-iodo-8-hydroxyquinoline-5-sulfonic acid: 1 mol / L acetate buffer (mixed at pH 5.0, volume ratio = 1: 2)) Was measured with a 10 mm cell, and the Al concentration in the sample water at each time was calculated in the same manner as in Example 4, and the following was calculated. The formula was used to calculate Al _{0. The} results are shown in Table 1.
Al ₀ + Al ₁ + Al ₂ = Al ₀ + Al ₁ (1- ^{et / t1} ) + Al ₂ (1- ^{et / t2} )
FIG. 3 shows changes in absorbance at a wavelength of 370 nm [(a)], changes in absorbance at a wavelength of 600 nm [(b)], and absorbance analysis results [(c)] and Al concentration calculation [(d)], respectively. Shown in the graph.

Comparative Example 1
Each solution prepared by using polyaluminum chloride and having an Al concentration of 4 mg / L as Al and sodium metasilicate so that the SiO ₂ concentration is 0, 25, 50 mg / L and pH 8.5 was used as sample water.
The aluminum concentration of the filtrate filtered with 0.2 μm filter paper was measured by ICP-MS, and the zeta potential was measured. As a result, the aluminum concentration was 2.76 mg / L (SiO ₂ = 0 mg / L) as Al, 1.37 mg / L (SiO ₂ = 25 mg / L) as Al, and 0.97 mg / L (SiO ₂ = L) as Al. 50 mg / L) and the zeta potential was +5 mV.
In FIG. 4, the correlation of Example 1, Example 3, and Comparative Example 1 is shown with a graph.

The following can be understood from Table 1 and FIG.
When Example 1 and Comparative Example 1 were compared, the correlation coefficient (R ² = 1) was high, and it was confirmed that there was a correlation between the technique of Example 1 and an Al concentration of 0.2 μm or less. When Example 1 (SiO ₂ = 25 mg / L) and Example 2 were compared with each other, an equivalent Al concentration was obtained. Thus, it can be seen that a solution prepared by mixing Ferron and an acetate buffer in advance may be used.
When Example 3 and Comparative Example 1 were compared, a high correlation (R ² = 0.96) was obtained, confirming that there was a correlation between the technique of Example 3 and an Al concentration of 0.2 μm or less. did it.
When Example 4 was compared with Example 1 (SiO ₂ = 25 mg / L) and Example 5 was compared with Example 3 (SiO ₂ = 25 mg / L), an equivalent Al concentration was obtained. Even so, it was found that the target Al concentration can be measured by measuring the absorbance at 600 nm.

Example 6
FIG. 5 is a schematic diagram of an apparatus for a simulated cooling water system having a heat capacity of 100 L of retained water.
A simulated cooling water system having a heat transfer area of 0.25 m ^{2 and a} heat capacity of 100 L (see schematic diagram of the apparatus) was used. The material of the heat exchanger 14 was SUS304, a tube having an outer diameter of 19 mm, and a non-heat transfer evaluation tube (SUS304, outer diameter 19 mm) 13 was provided in the system.
Actual industrial water (Kawasaki Industrial Water) was added as makeup water and operated. The silica concentration was 25 mg / L, and the aluminum concentration was 0.5 mg / L as Al.
The operation was performed for 30 days while controlling blow water (exhaust of circulating water outside the system) so that the concentration factor was 5 times.
During this time, the inlet temperature of the circulating water heat exchanger was kept at 30 ° C., and the outlet temperature was kept at 40 ° C. Moreover, the flow velocity which passes the non-heat-transfer evaluation tube 13 of circulating water was 0.5 m / s.
As a calcium-based scale adhesion inhibitor, hydroxydiethylidenephosphonic acid is used as PO ₄ , and 6 mg / L as PO _4. As a silica-based scale adhesion inhibitor, acrylic acid / sulfonic acid / N-vinylpyrrolidone copolymer is used as a chemical injection control device. Was added using. In the slime control treatment, sodium hypochlorite was added to the cooling water system using a chemical injection pump so as to be 0.5 to 1.0 mg / L as Cl ₂ , and was operated for 30 days.
When the aluminum concentration involved in silica-based scale formation is 0.09 mg / L or less as Al, it is 10 mg / L as a solid, and when Al is 0.1 to 0.14 mg / L as a solid, In the case of 12.5 mg / L and 0.15 to 0.19 mg / L as Al, 15 mg / L was added as a solid.
Moreover, in the Al concentration automatic measuring apparatus, the Al concentration was measured by the method of Example 2.
Thereafter, the amount of scale adhered to the non-heat transfer tube was measured to evaluate the antifouling effect. The results are shown in Table 2.
FIG. 6 is a graph showing the results of control using an Al concentration automatic measuring apparatus.

Comparative Example 2
Except for the addition method of the silica-based scale adhesion inhibitor, evaluation was performed with a simulated cooling water system in the same manner as in Example 6. The silica-based scale adhesion inhibitor was quantitatively determined to be 5 mg / L, 10 mg / L, and 15 mg / L. Injection was added. The results are shown in Table 2.

From Table 2, when Example 6 and Comparative Example 2 are compared, it can be seen that Comparative Example 2 can reduce scale adhesion due to the addition of 15 mg / L. However, at 10 mg / L or less, the scale deposition rate cannot be reduced sufficiently.
On the other hand, in Example 6, it turned out that it can reduce to the scale adhesion rate equivalent to 15 mg / L addition by the usage-amount of a small scale inhibitor by using a chemical injection control apparatus.

  The aluminum concentration measurement method of the present invention can effectively measure the concentration of aluminum that causes silica-based scale adhesion in water to be treated in a cooling water system, a boiler water system, and the like, and based on the aluminum concentration. The concentration of the silica-based scale adhesion inhibitor added to the treatment target can be controlled. Moreover, the aluminum concentration measuring method of the present invention can be automated. Furthermore, the aluminum concentration automatic measuring device of the present invention can measure the aluminum concentration on site.

DESCRIPTION OF SYMBOLS 1 Channel of target water 2 Flow control valve 3 Strainer 4 Automatic measuring device 5 Control part 6 Water treatment agent storage tank 7 Treatment agent addition path 11 Circulating water pit 12 Circulating pump 13 Non-heat transfer tube 14 Heat exchanger 15 Level sensor 16 Conductivity Total 17 Blow piping 18, 19 Chemical injection pump 20 Replenishment water pump 21 Scale adhesion inhibitor 22 Sodium hypochlorite tank 23 Replenishment water tank 24 Aluminum concentration automatic measuring device 401 Supply path 402 Reaction reagent layer 403 Reagent injection path 404 Optical measurement section 405 Measurement cell 406 Light source 407 Light receiving unit 408 Discharge path 409 Analysis unit P1 Reaction reagent injection pump P2 Treatment agent injection pump

Claims (10)

  A method for measuring the concentration of aluminum that causes silica-based scale in test water, comprising adding a reaction reagent comprising a combination of 7-iodo-8-hydroxyquinoline-5-sulfonic acid and a buffer to the test water Thereafter, the aluminum concentration is determined from the absorbance measured at the aluminum analysis wavelength.   After adding the reaction reagent to the test water, the absorbance is measured at the aluminum analysis wavelength and the iron analysis wavelength, and the iron concentration is determined from the absorbance at the iron analysis wavelength. Based on this iron concentration, the absorbance of the iron contribution at the aluminum analysis wavelength The method for measuring aluminum concentration in test water according to claim 1, wherein the aluminum concentration is determined from the absorbance obtained by removing the absorbance of the iron contribution from the absorbance at the aluminum analysis wavelength.   The method for measuring an aluminum concentration in test water according to claim 1 or 2, wherein the absorbance is measured within 1 minute after the addition of the reaction reagent.   2. The change in absorbance with time after addition of a reaction reagent is measured, the aluminum concentration at each time is calculated, and the obtained aluminum concentration at 0 minutes is calculated by nonlinear analysis of the change over time in the obtained aluminum concentration. Or the aluminum concentration measuring method in the test water of 2.   A method of automatically measuring the concentration of aluminum that causes silica-based scale in test water, the step of continuously passing the test water through an optical measurement unit, 7-iodo-8-hydroxyquinoline-5-sulfonic acid, A step of adding a reaction reagent comprising a combination with a buffer solution to the test water to form a measurement sample solution, and a step of automatically measuring the aluminum concentration in the measurement sample solution in the optical measurement unit, A method for automatically measuring an aluminum concentration in test water, characterized by comprising at least:   The method for automatically measuring aluminum concentration in test water according to claim 5, wherein the absorbance is measured within 1 minute after the addition of the reaction reagent.   6. The time-dependent change in absorbance after the addition of the reaction reagent is measured, the aluminum concentration at each time is calculated, and the obtained aluminum concentration at 0 minutes is calculated by nonlinear analysis of the change over time in the obtained aluminum concentration. The method for automatically measuring the aluminum concentration in the test water described in 1.   The apparatus according to claim 5, further comprising means for mixing the reaction reagent solution diluted in advance and the test water so that the aluminum concentration in the measurement sample water falls within a quantitative range in which the calibration curve for optical measurement shows linearity. Automatic measurement method of aluminum concentration in test water.   An apparatus for automatically measuring the concentration of aluminum that causes a silica-based scale in the test water, the means for continuously passing the test water through the optical measurement unit, 7-iodo-8-hydroxyquinoline-5-sulfonic acid, Means for adding a reaction reagent comprising a combination with a buffer solution to the test water to form a measurement sample solution, and means for automatically measuring the aluminum concentration in the measurement sample solution in the optical measurement unit; An apparatus for automatically measuring aluminum concentration in test water, characterized by comprising at least.   The silica-based scale in the test water obtained by the aluminum concentration measuring method in the test water according to any one of claims 1 to 4 or the aluminum concentration automatic measuring method in the test water according to any one of claims 5 to 8. A method for controlling the concentration of a silica-based scale adhesion inhibitor characterized by controlling the amount of the silica-based scale adhesion inhibitor added to the water to be treated of the water sampling source based on the concentration measurement data of aluminum as a factor.

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