JP2002040010A - Coloring film carrying phosphoric acid reactive reagent, and phosphoric acid concentration measuring device using coloring film carrying phosphoric acid reactive reagent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems in conventional phosphoric acid concentration measurement that measuring treatment is complicated because a wet measuring device using a liquid reagent is used and that the system is limited because comparison determination is executed by visual observation by a person. SOLUTION: A dry coloring film formed by carrying a reagent for developing a color by reacting with phosphoric acid on a transparent film is used, and the coloring film is dipped in a test body solution, and then optical absorptivity is measured, to thereby quantitate the phosphoric acid concentration in the test body solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color-developing film carrying a phosphoric acid reagent and a phosphoric acid concentration measuring device using the color film carrying a phosphoric acid reagent.

2. Description of the Related Art In recent years, pollution of the water environment due to domestic wastewater and the like has become a problem as part of environmental measures, and efforts to purify the water environment have become a social issue. Particularly in domestic wastewater, phosphorus contained in detergents and the like is a major contaminant of wastewater, and therefore, development of these removal systems is being promoted. For example, a system is being developed that is attached to a wastewater treatment / purification tank to generate iron ions by electrolysis and precipitate and remove phosphorus in the wastewater as iron phosphate. In the conventional phosphorus removal system, it is necessary to measure the concentration of phosphorus contained in the wastewater in advance and operate the removal system based on the measured concentration. For example, in the above-mentioned system, since the amount of iron electrolysis is set, if the phosphorus concentration in the wastewater changes greatly, iron ions become excessive or deficient, so the phosphorus concentration in the wastewater is constantly measured and feedback control is performed. It is required to apply. Conventionally, the measurement of phosphorus concentration is generally performed by measuring the concentration of phosphoric acid in a solution. Conventionally, a simple method for measuring the phosphorus concentration is to add a solution in which phosphoric acid is dissolved to a liquid reagent that reacts with phosphoric acid to develop a color, and visually check the color intensity of the developed reagent. There is a method in which a phosphoric acid concentration associated with a sample having the same color density is read by comparing with a color sample prepared in advance.

As described above, the conventional phosphorus concentration measurement is a wet type measurement device using a liquid reagent, so that the measurement process is complicated, and the concentration determination can be made by human eyes. As a result, the accuracy is limited, and improvement of these issues is required.

SUMMARY OF THE INVENTION The present invention realizes a dry-type color-developing film in which a transparent film carries a reagent which develops a color in response to phosphoric acid. Further, the present invention is a phosphoric acid concentration measuring device for measuring the concentration of phosphoric acid in a solution,
A dry-type color-developing film in which a reagent that develops a color in response to phosphoric acid is supported on a transparent film; a light-absorbance measuring means for measuring the light-absorbance of the color-developed film in response to phosphoric acid in a solution; The present invention provides a phosphoric acid concentration measuring device comprising output means for outputting the concentration of phosphoric acid in a solution based on the light absorbance measured by the means. According to the present invention, it is possible to perform light absorption measurement with high measurement accuracy. Furthermore, since a dry-type reagent can be used for that purpose, the measurement process is not complicated and comfortable.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The production conditions of a color-developing film and the use conditions of a phosphoric acid concentration measuring device using this color-developing film will be described below. First, a film was formed by applying a 10 mil, 30 mil, 50 mil, and 75 mil bar coater on a glass preparation. This cast solution was prepared by mixing a polyvinyl alcohol aqueous solution and a mixed solution of ammonium molybdate and ascorbic acid. For film thickness measurement,
After drying at room temperature, it was immersed in several types of phosphoric acid solutions having different concentrations in the range of 0 to 50 ppm for a certain period of time using a stylus type profilometer, dried at room temperature, and then measured at 800 nm with a spectrophotometer (type 330, manufactured by Hitachi, Ltd.). The absorbance was measured, and the relationship between the film thickness, the immersion time in the phosphoric acid solution and the quantitative property was as follows. (1) A mixed solution of ammonium molybdate-ascorbic acid usually shows a yellow color due to oxidation when left for one day.
It turns brown and deteriorates in about a day. However, it was shown that light yellow could be maintained for 3 days by mixing with the aqueous polyvinyl alcohol solution as described above, and deterioration was suppressed. (2) Water was added to 30 g of an aqueous solution of polyvinyl alcohol, and the mixture was heated and dissolved at 70 ° C. at 100 ° C. to form a highly viscous solution. Then, a cast solution containing 60 ml of a mixed solution of ammonium molybdate-ascorbic acid was added to 10 or 3
By coating with a 0, 50, and 75 mil bar coater, films having a thickness of about 6, 14, 21, and 30 μm, respectively, could be formed. When this was immersed in a phosphoric acid solution for 30 seconds, a film thickness of about 6, 14 μm formed at 10, 30 mils
As shown in FIG. 4, a proportional relationship was established between the phosphoric acid concentration and the absorbance. However, films made at 50 and 75 mils showed a proportional relationship up to 20 ppm, but showed lower absorbance at 50 ppm. (3) When the time of immersion in the phosphoric acid solution was changed between 2 seconds and 5 minutes for the film prepared at 50 mil, the immersion time of 2 seconds and 10 seconds was proportional to the phosphoric acid concentration and the absorbance. I couldn't. 30 seconds immersion to 20ppm, 1
In the minute immersion, there was a proportional relationship up to 30 ppm. Also, 5
In the minute immersion, as is apparent from the relationship between the absorbance and the phosphoric acid concentration in FIG. 3, a proportional relationship up to 50 ppm was recognized, indicating that immersion was necessary until the reaction was completed in the film. As described above, it has been clarified that by optimizing the film thickness and the immersion time so that the color is completely formed in the color developing film, it is possible to reliably determine 0 to 50 ppm of phosphoric acid. Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, FIG. 1 shows a color developing film of the present invention. In FIG. 1, reference numeral 1 denotes a transparent substrate, and a transparent material in a visible region such as glass, polyvinyl chloride, or polyethylene terephthalate can be used. Reference numeral 2 denotes a reagent layer, and the transparent substrate 1 is coated with a reagent. As this reagent, a factory drainage test method (JISK
[0102] The molybdenum blue (ascorbic acid reduction) reagent specified in 0102) is used. In this case, a mixed solution of ammonium molybdate and aucorbic acid can be used. Examples of a method for coating such a reagent on the transparent substrate 1 include coating, dip coating, spin coating, and vapor deposition, and it is necessary that the film thickness be uniform. To ensure uniformity of the film thickness, the viscosity of the reagent is required to some extent, but when the viscosity is low and it is difficult to control the film thickness, a water-soluble polymer such as polyvinyl alcohol may be dissolved in the reagent. it can. That is, if the viscosity of the solution of the reagent (cast solution) is too low, the solution drips out of the substrate 1 and the required film thickness cannot be secured, and if the viscosity is too high, the solution solidifies while the surface is uneven. Therefore, it is necessary to appropriately control the film thickness. The subsequent drying treatment is preferably performed at room temperature for about 3 hours. After the color film is immersed in a sample solution (such as domestic wastewater containing phosphoric acid), the film is lifted, and after a certain period of time, the absorbance is measured. At this time, the phosphoric acid in the solution reacts with the reagent solution of ammonium molybdate to form a heteropoly compound.
This heteropoly compound is reduced with ascorbic acid,
Molybdenum blue is produced and the color-developing film develops a blue color. Note that tin chloride can be used instead of ascorbic acid. FIG. 2 shows the configuration of the phosphorus concentration measuring device. In the figure, reference numeral 10 denotes a color developing film. Reference numeral 20 denotes an emission light source that irradiates light to the color-developing film, and includes an LED whose emission wavelength corresponds to the absorption wavelength range of the reagent of the color-developing film. Reference numeral 30 denotes a light receiving element that receives transmitted light from the color-developing film and detects the degree of light absorption, and includes a photodiode corresponding to the absorption wavelength range of the reagent of the color-developing film. The LED and the photodiode constitute a photocoupler. Reference numeral 40 denotes a table having a relationship between the light absorbance and the concentration of phosphoric acid (substantially proportional as shown in FIG. 3), and is constituted by a semiconductor memory. The table 40 outputs the phosphoric acid concentration of the sample based on the light absorbance detected by the light receiving element 30. A display device 50 displays the phosphoric acid concentration obtained from the table 30 in an analog or digital format. The conditions of the above reagents and the film forming method are summarized as follows, and it was confirmed that the concentration of phosphoric acid can be measured up to 50 ppm. (1) A color developing film is formed by forming a reagent layer on a glass preparation. (2) The structure of the color-forming film is a single-layer structure in which a color-forming reagent is mixed in a water-absorbing polymer. (3) The material of the coloring film is polyvinyl alcohol resin. (4) Ascorbic acid reducing reagent of JIS K0102 is used as a coloring reagent. (5) The casting solution is a polyvinyl alcohol resin 30
g and water, and after dissolving at 100 ° C., add 60 ml of the coloring reagent solution. (6) The film was applied using a bar coater # 50 mil and dried at room temperature to obtain a dry color developing film. The film thickness is about 20 μm. (7) The immersion time in the phosphoric acid solution is about 5 minutes. In the above description, the dry type color film formed by coating, vapor deposition, or casting the reagent layer 2 that develops a color in response to phosphoric acid has been described. It is also possible to employ a substrate in which the surface of the substrate, such as a transparent porous chamber substrate, a ground glass substrate, or the like, or a water-absorbent substrate is impregnated with the reagent to be dried.

As described above, according to the present invention, it is possible to perform light absorption measurement with high measurement accuracy. further,
Since a dry-type coloring film can be used, the measurement process can be prevented from becoming complicated.

[Brief description of the drawings]

FIG. 1 is a perspective view of a light emitting film of the present invention.

FIG. 2 is a configuration diagram of a phosphoric acid concentration measuring device of the present invention.

FIG. 3 is a diagram showing the relationship between the degree of absorption and the concentration of phosphoric acid.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Reagent layer 10 Light emitting film 20 LED 30 Photodiode 40 Table 50 Display

Claims (2)

[Claims] 1. A dry color-developing film comprising a transparent film carrying a reagent which develops a color in response to phosphoric acid. 2. A phosphoric acid concentration measuring device for measuring the concentration of phosphoric acid in a solution, comprising a dry color developing film in which a reagent that develops a color in response to phosphoric acid is carried on a transparent film, and a phosphoric acid in the solution. Phosphoric acid concentration measurement comprising light absorbance measuring means for measuring the light absorbance of the color-developing film, and output means for outputting the concentration of phosphoric acid in the solution based on the light absorbance measured by the light absorbance measure. apparatus.