JP6236874B2 - Anionic polymer concentration measuring method and apparatus - Google Patents

Description

  The present invention relates to a method and an apparatus for measuring the concentration of an anionic polymer for water treatment added to a water system equipped with a steam generating facility such as a cooling water system or a boiler.

  Acrylic polymer, acrylic acid copolymer, maleic acid polymer, maleic acid copolymer for water treatment purposes, such as water scale with corrosion generating equipment such as cooling water and boilers, corrosion and dirt prevention Anionic polymers such as are added. An anionic polymer is a high-performance scale inhibitor, but in order to fully exhibit the scale preventive ability, it is extremely important to control the concentration of the anionic polymer in the target aqueous system. As a method for measuring the concentration of such anionic polymer in water, Patent Document 1, after collecting sample water from an aqueous system, adding a reagent to react with the anionic polymer to cause white turbidity, and the wavelength is 400 to 900 nm. A method is described in which measurement is performed using a portable measuring device that can be turbidized by irradiation with any visible light (Claim 1 of Patent Document 1). In Patent Document 1, this portable measuring device includes a lidded measuring cell, an opening in which the measuring cell can be mounted, a visible light irradiation unit provided on a side surface of the opening, and transmitted light or reflected light. Obtained by an optical measurement unit comprising a light receiving unit that receives light, a light shielding cap that covers and covers the optical measurement unit, a data processing unit that receives and calculates an electrical signal from the optical measurement unit, and a data processing unit It is comprised from the display part which displays the result (same, Claim 5).

JP 2006-38462 A

  In the method for measuring an anionic polymer disclosed in Patent Document 1, in order to perform an accurate measurement, it is necessary to collect an accurate amount of a plurality of reagents and sample water. In addition, if the stirring performed between each operation is insufficient, even if the sample water does not contain an anionic polymer component, the reagents come into contact with each other at a high concentration, resulting in white turbidity and positive measurement results. There was an error.

  An object of this invention is to provide the measuring method and apparatus of an anionic polymer density | concentration which can measure the density | concentration of the anionic polymer in water easily and accurately.

  The method for measuring the concentration of an anionic polymer of the present invention is a method for measuring the concentration of an anionic polymer in an aqueous system, and after injecting a sample collected from the aqueous system into a measurement cell in which an aqueous solution of a chelating agent is previously enclosed, Add an aqueous solution of a quaternary ammonium salt, stir to react with the anionic polymer to cause white turbidity, measure the transmittance or absorbance of any visible light having a wavelength of 400 to 900 nm, and measure the concentration of the anionic polymer Is measured.

  Examples of the anionic polymer include an acrylic acid polymer or copolymer, a maleic acid polymer or copolymer, and the like.

  An anionic polymer concentration measuring device of the present invention receives a measurement cell in which an aqueous solution of a chelating agent is encapsulated in advance, an optical measurement unit for measuring the absorbance or transmittance of the measurement cell, and a signal from the optical measurement unit. It is a portable anionic polymer concentration measuring device in an aqueous system, including a data processing unit for calculation and a display unit for displaying a result obtained by the data processing unit.

  In the present invention, since the aqueous solution of the chelating agent is enclosed in the measurement cell in advance, the operation of injecting the cell into the cell at the measurement site is only two operations of the test water injection operation and the quaternary ammonium salt aqueous solution injection operation. It becomes. For this reason, the density | concentration of an anionic polymer can be measured easily. Moreover, the concentration of the anionic polymer can be accurately measured by enclosing a predetermined amount of an aqueous solution of a chelating agent having a specified concentration in the measurement cell.

It is a graph which shows the measurement result of an Example. It is a graph which shows the measurement result of a comparative example.

  In the anionic polymer concentration measuring method of the present invention, after injecting a sample collected from an aqueous system into a measuring cell in which an aqueous solution of a chelating agent is encapsulated in advance, a quaternary ammonium salt is added and stirred to react with the anionic polymer. The concentration of the anionic polymer is measured by measuring the transmittance or absorbance of visible light having a wavelength of 400 to 900 nm.

  The method of the present invention utilizes a phenomenon in which an anionic polymer in water reacts with a quaternary ammonium salt to quantitatively produce an insoluble substance in water, and the sample water becomes clouded. Based on knowing the concentration of anionic polymer.

  The anionic polymer in the present invention is a water-soluble polymer compound having a molecular weight of 500 or more having a plurality of carboxyl groups or sulfonic acid groups in the molecule, and is added for the main purpose of preventing corrosion and preventing scale in aqueous systems. It is. Examples of anionic polymers include acrylic acid mono- or copolymers, maleic acid mono- or copolymers, itaconic acid mono- or copolymers, 2-acrylamido-2-methylpropanesulfonic acid mono- or copolymers. 1 type or 2 types or more, such as a mono- or copolymer, a mono- or copolymer of allyl hydroxypropane sulfonic acid, etc. are mentioned.

  The anionic polymer concentration in the test water to be measured is preferably about 0.1 to 500 mg / L, particularly about 1 to 50 mg / L.

  The sample water to be measured may contain corrosion prevention, scale prevention, slime control agent and the like in addition to the anionic polymer.

  The chelating agent used in the present invention masks the metal ions coexisting in the sample water from interfering with the quantitative reaction between the quaternary ammonium salt and the anionic polymer electrolyte, and the quaternary ammonium salt and the anionic high salt. This influences the precipitation reaction with the molecular electrolyte and ensures the linearity of the calibration curve in the high concentration region of the anionic polymer electrolyte. A chelating agent may be added as a salt to act as a pH buffer during the reaction. As chelating agents, aminocarboxylic acids such as ethylenediaminetetraacetate (EDTA), nitrilotriacetate, diethylenetriaminepentaacetate, and hydroxy acids such as citrate, malate, tartrate, glycolate can be used. These may be used alone or in combination of two or more. The salt here is sodium salt, potassium salt, lithium salt, ammonium salt, amine salt and the like.

  The concentration of the chelating agent aqueous solution sealed in the cell is preferably about 100 to 10000 mg / L, particularly about 1000 to 5000 mg / L.

  In the present invention, a cell made of a synthetic resin such as polystyrene, polyethylene, polypropylene, polymethyl methacrylate, and polycarbonate is preferable as the cell in which the chelating agent aqueous solution is sealed. The cell is provided with a removable sealing lid, and it is preferable to remove the sealing lid and add test water or the like to the cell for measurement.

  A commercially available product can be used as such a synthetic resin cell. Commercially available cells include those made of polystyrene, having an optical path length of 10 mm, an optical path width of 10 mm, a height of 45 mm, and an outer width of 12.5 mm. After injecting 1 to 3 mL of chelating agent aqueous solution into this cell, a lid made of polystyrene, polyethylene, polypropylene, polymethyl methacrylate, polycarbonate, etc. is airtightly attached to the upper end surface of the cell with a polyester thermal adhesive film to chelate. Enclose the agent aqueous solution.

  When injecting test water into this cell, it is preferable to inject it so that the water level in the cell after injection is 20 to 40 mm.

  After injecting test water into the cell, an aqueous solution of a quaternary ammonium salt is added to the cell. The quaternary ammonium salt used in the present invention may be any quaternary ammonium salt as long as it reacts quantitatively with an anionic polymer to produce a stable white turbidity, preferably a quaternary ammonium salt having 12 or more carbon atoms. is there. Specific examples of quaternary ammonium salts include tetraalkylammonium salts, trialkylbenzylammonium salts, dialkyldibenzylammonium salts, alkyltribenzylammonium salts, benzethonium salts, benzalkonium salts, alkylpyridinium salts, imidazolinium Salts as well as their derivatives. The quaternary ammonium salt may have two or more quaternary ammonium groups in the molecule. Examples of such a compound include poly [oxyethylene (dimethylimino) ethylene (dimethylimino) ethylene dichloride], polydiallyl. Examples include dialkylammonium salts, poly (meth) acryloyloxyalkyltrialkylammonium salts, poly (meth) acrylamide alkyltrialkylammonium salts, and the like. Examples of the quaternary ammonium salt include chloride, bromide, iodide, sulfate and the like.

  The concentration of the aqueous quaternary ammonium salt solution added to the cell is preferably 1 to 5000 mg / L, particularly preferably about 100 to 1000 mg / L.

  A preferable measuring device for use in the present invention is a measuring cell with a lid encapsulating a chelating agent in advance, a measuring cell with a wavelength of 400 to 900 nm, which can be equipped with the measuring cell, and a visible light irradiation unit. An optical measurement unit comprising a light receiving unit that receives the transmitted or reflected light, a light shielding cap that covers and covers the optical measurement unit, and data processing that receives and calculates an electrical signal from the optical measurement unit And a display unit for displaying the result obtained by the data processing unit.

  Bring this portable anionic polymer measuring device to the water system in which the concentration of the anionic polymer in the water is to be measured, and inject the sampled water collected from the target water system into the measuring cell in which the chelating agent is enclosed. Accurately measure the sample injection rate.

  Next, an aqueous quaternary ammonium salt solution is added to the measurement cell and stirred. In order to perform this stirring, it is preferable to attach a lid to the cell and shake it several times.

  An aqueous quaternary ammonium salt solution is added to the cell so that more quaternary ammonium salt is added than is necessary to react with the anionic polymer to produce a stable cloudiness. When analyzing outdoors, it is preferable to use an eye drop container that can be dropped in a volume of several tens of μL.

  If the concentration of the quaternary ammonium salt aqueous solution is selected so that a sufficient SN ratio can be obtained even if the turbidity of the measurement target is not subjected to zero point correction, before dropping the aqueous solution of the quaternary ammonium salt, There is no need to perform zero correction of the measuring device. The transmittance or absorbance of the chelating agent aqueous solution and test water before adding the quaternary ammonium salt aqueous solution is measured in advance, and then the transmittance of the cell after adding the quaternary ammonium salt aqueous solution. Alternatively, the absorbance can be measured, and the concentration of the anionic polymer in the test water can be calculated from the difference between the two.

  The wavelength to be used may be arbitrarily selected from 400 to 900 nm as long as the cloudiness can be accurately captured. Currently, a handy type simple measuring device using a fixed wavelength for the purpose of measuring a specific compound is commercially available. Of these, in the present invention, it is preferable to use POCKET COLORIMTER II manufactured by HACH, which uses visible light having a wavelength of 500 to 550 nm for residual chlorine measurement, because it can be carried out easily and accurately. Especially in the large-scale water system of a complex, chlorine is usually used as a slime control measure, and the chlorine concentration using the above apparatus is frequently measured. Therefore, when the above apparatus is used, the residual chlorine concentration and the anionic polymer concentration can be measured only by changing the cell and the reagent, which is very convenient.

  When using the measuring apparatus according to the present invention, as in a general measuring apparatus, the concentration of the anionic polymer standard product to be measured is measured in advance, and the output of the measuring apparatus (in the case of the apparatus, the indicated value) A calibration curve representing the relationship between the anionic polymer and the output value is prepared.

  In addition, about the temperature at the time of measurement, normal temperature (about 10-30 degreeC) may be sufficient.

  When compounds such as polyphenols that affect the cloudiness reaction with an anionic polymer coexist in the sample water, the affected substance is decomposed using an oxidizing agent, etc. Measure the concentration.

[Comparative Example 1]
Sample water containing sodium polyacrylate 5,10,15,20mg / L as anionic polymer, measuring cell (made of polystyrene, optical path length 10mm, optical path width 10mm, height 45mm, outer width 12.5mm) After collecting 4 mL, it was capped and shaken several times.

  Next, the cell was attached to a POCKET COLORIMTER II manufactured by HACH, and the entire optical measurement unit was covered with a light-shielding cap, and the first irradiation was performed using visible light having a wavelength of 528 nm, and zero correction was performed. Next, remove the cap, take out the cell, remove the lid, add 2 mL of a reagent containing 2% by weight of EDTA and 4 mL of a reagent containing 0.1% by weight of benzethonium chloride, and cover the lid. Shake several times. Then, it was reattached to the optical measurement part of the said apparatus, covered with the light-shielding cap, and left to react for 5 minutes. Thereafter, visible light having a wavelength of 528 nm was irradiated to measure the absorbance. A calibration curve was prepared by plotting the indicated value of the measuring apparatus and the polyacrylic acid sodium concentration on a graph. The results are shown in FIG.

[Example 1]
The measurement was performed using a cell made of polystyrene, having an optical path length of 10 mm, an optical path width of 10 mm, a height of 45 mm, and an outer width of 12.5 mm, in which 1.5 mL of an EDTA 0.7% by weight aqueous solution was sealed. The lid of the cell was removed, and 1 mL of test water composed of an aqueous sodium polyacrylate solution having the same concentration as in Comparative Example 1 was added, and then a 5 wt% aqueous solution of benzethonium chloride was added dropwise with an about 20 μL dropper. Otherwise, the measurement was performed in the same manner as in Comparative Example 1, and a calibration curve was created by plotting the measurement apparatus instruction value and the sodium polyacrylate concentration on a graph. The results are shown in FIG.

  In Comparative Example 1, it is necessary to collect a total of three types of solutions including test water and two types of reagents and mix them in a colorimetric cell. In Example 1, in a colorimetric cell in which a chelating agent aqueous solution is previously sealed, Since only water and a quaternary ammonium salt aqueous solution are added, the uncertainty of the amount of water collected during weighing is greatly reduced, and the measurement accuracy is improved. Also, the measurement operation is easy.

  In general, the reason for zero adjustment (also referred to as background correction) is to subtract from cell differences and contamination and from the sample itself (buffer absorption, insoluble effects, etc.) . In Example 1, by using an industrially manufactured synthetic resin cell, the influence of individual cell differences and dirt are eliminated.

  The variation in absorbance when pure water was added to the colorimetric cell enclosing the reagent used in Example 1 was less than 0.01, and zero adjustment was unnecessary.

Claims (3)

A method for measuring the concentration of an anionic polymer in an aqueous system,
After injecting test water sampled from the water system into a measurement cell in which an aqueous solution of a chelating agent is encapsulated in advance, an aqueous solution of a quaternary ammonium salt is added and stirred to react with an anionic polymer to produce white turbidity, and the wavelength is 400 A method for measuring the concentration of an anionic polymer, comprising measuring the transmittance or absorbance of visible light of any of ˜900 nm to measure the concentration of the anionic polymer.   The concentration measurement of an anionic polymer according to claim 1, wherein the anionic polymer is at least one selected from the group consisting of an acrylic acid polymer or copolymer, a maleic acid polymer or a copolymer. Method. A measurement cell encapsulating a chelating agent in advance;
An optical measurement unit for measuring the absorbance or transmittance of the measurement cell;
A data processing unit that receives and calculates a signal from the optical measurement unit;
A display unit for displaying the results obtained by the data processing unit;
A device for measuring the concentration of an anionic polymer in an aqueous system that is portable.

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