Method for measuring ph of test water

A measurement method and a technology with a specified range, which are applied in the direction of material inspection products, water testing, and material analysis through observation of the impact on chemical indicators, etc., and can solve problems such as narrowing

Inactive Publication Date: 2020-11-27
MIURA COMPANY LIMITED
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, since the color-changing region of the pH indicator is limited to a certain range, the range of pH that can be measured by the above-mentioned alternative method is at most about 1 to 2, which is relatively narrow.

Method used

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  • Method for measuring ph of test water
  • Method for measuring ph of test water
  • Method for measuring ph of test water

Examples

Experimental program
Comparison scheme
Effect test

no. 1 Embodiment approach example

[0042] This embodiment example is an example in which the pH of the test water can be measured in the range of approximately 4 to 9 (this range includes the entire buffer pH range of carbonic acid), and contains the following chromogenic reagents.

[0043] ◎The first chromogenic reagent

[0044] Selected from chromogenic reagents with a pKa in the range of 4.1 to 6.0. For example, it may be selected from methyl red (pKa: 5.1), bromophenol blue (pKa: 4.2) and bromocresol green (pKa: 4.7).

[0045] ◎The second chromogenic reagent

[0046] Selected from chromogenic reagents with a pKa in the range of 6.5 to 8.5. For example, it may be selected from phenol red (pKa: 1.2 and 7.7), neutral red (pKa: 6.7 and 7.4) and cresyl red (pKa: 1.0 and 8.0).

[0047] ◎The third chromogenic reagent

[0048] Selected from chromogenic reagents with a pKa in the range of 5.5 to 7.5. For example, it may be selected from bromocresol purple (pKa: 6.3) and bromothymol blue (pKa: 7.1).

[0049] Sp...

no. 2 Embodiment approach example

[0065] This embodiment example is an example in which the pH of test water can be measured in the range of approximately 4 to 12 (this range also includes the entire buffer pH range of carbonic acid), and contains the following chromogenic reagents.

[0066] ◎The first chromogenic reagent

[0067] Selected from chromogenic reagents with a pKa in the range of 4.1 to 6.0. For example, it may be selected from methyl red (pKa: 5.1), bromophenol blue (pKa: 4.2) and bromocresol green (pKa: 4.7).

[0068] ◎The second chromogenic reagent

[0069] Selected from chromogenic reagents with a pKa in the range of 8.5 to 11.5. For example, it may be selected from Alizarin Yellow (pKa: 11.06) and Thymol Blue (pKa: 1.7 and 8.9).

[0070] ◎The third chromogenic reagent

[0071] Two kinds of color-developing reagent A selected from the color-developing reagents whose pKa is in the range of 5.5 to 7.5, and color-developing reagent B selected from the color-developing reagents whose pKa is in ...

Embodiment

[0139] 500 g of reagent compositions having the compositions shown in Table 5 were prepared. This reagent composition corresponds to the reagent composition listed as a specific example of the reagent composition of the first embodiment.

[0140] [table 5]

[0141] table 5

[0142]

[0143] Assuming that 100mL test water added with 0.75g of reagent composition is irradiated with visible light with wavelengths of 420nm, 525nm and 590nm, according to the above formula (1), formula (2) and formula (3) and Henderson-Hassell Balcher's formula calculates the absorbance of visible light at each wavelength predicted in this case. Here, the absorbance of the above-mentioned visible light of each wavelength is calculated for the test water whose pH is different in the range of 1 to 10 at intervals of 0.1.

[0144] According to the calculated absorbance of each wavelength, the relationship between the pH value of the test water and the absorbance ratio (525nm / 420nm) and the relatio...

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Abstract

A reagent composition is added to test water, the reagent composition being prepared by dissolving methyl red having an acid dissociation constant (pKa) of 5.1, phenol red having a pKa of 7.7 (higherthan that of the methyl red), and bromocresol purple having a pKa of 6.3 (between those of methyl red and phenol red) at respective prescribed proportions in ethylene glycol or another such diol. Thelight absorbance of the test water to which the reagent composition was added is measured with respect to three wavelengths, i.e., a wavelength selected from the range of 410-430 nm, a wavelength selected from the range of 515-535 nm, and a wavelength selected from the range of 580-600 nm, and the pH of the test water is assessed on the basis of the light absorbance. This makes it possible to measure the pH of the test water within a range of 4-9.

Description

technical field [0001] The present invention relates to a method for measuring the pH of test water, in particular to a method for measuring the pH of test water within a specified range. This application claims priority based on Japanese Patent Application No. 2018-126856 filed in Japan on July 3, 2018, the contents of which are incorporated herein. Background technique [0002] Various types of water, such as boiler feed water and circulating cooling water for cooling towers, may have pH (hydrogen ion index) adjusted by adding chemicals. In this case, it is necessary to measure the pH of the water after adding the chemical, and to confirm that the pH of the water is adjusted to the target range. [0003] As general methods for measuring the pH of water or a solution, Patent Document 1 proposes a titration method and a measurement method using a glass electrode. However, in the titration method as described in Patent Document 1, when the sample, that is, the test water co...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/80G01N21/77G01N31/22
CPCG01N21/80G01N31/22G01N33/18G01N21/77
Inventor 浜田裕介石原由贵
Owner MIURA COMPANY LIMITED
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