JP3316657B2 - Nonionic surfactant concentration measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the concentration of a nonionic surfactant required for treating wastewater.

[0002]

2. Description of the Related Art Conventionally, in the method of detecting the concentration of a surfactant in water, the method of detecting the concentration of an anionic surfactant or a cationic surfactant includes a method of measuring conductivity, a method of measuring pH, There was a method by titration using a chemical solution. On the other hand, as a method for detecting the concentration of a nonionic surfactant, there is a method in which a certain amount of water to be measured is dried and the weight of a solid content is measured.

However, as a method of detecting the concentration of a nonionic surfactant, a method of drying a predetermined amount of water to be measured and measuring the solid content weight requires a long time to evaporate the water, When solids other than the nonionic surfactant are present, the measurement becomes difficult. In addition, since nonionic surfactants are nonionic as their name suggests, it is difficult to measure with conductivity and pH, and in order to perform titration with a chemical solution, a pretreatment with a strong acid or strong alkali is required. There was a problem that it took time and effort.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method which solves the above-mentioned problems of the prior art, that is, a method for simply detecting the concentration of a nonionic surfactant.

[0005]

According to the present invention, air is blown into an aqueous phase diluted with water so that the concentration of the nonionic surfactant in the water is equal to or lower than the critical micelle concentration, and foaming occurs. There is provided a method for measuring the concentration of a nonionic surfactant, which comprises detecting a physical state of a foam. According to the present invention, the aqueous phase diluted with water such that the concentration of the nonionic surfactant in the water is equal to or lower than the critical micelle concentration is foamed by applying vibration, and the physical state of the generated foam is detected. A method for measuring the concentration of a nonionic surfactant is provided. According to the present invention, there is provided a method for measuring the concentration of a nonionic surfactant, wherein the means for detecting the physical state of the foamed foam is a means for detecting the size of the generated foam. You. Further, according to the present invention, there is provided a method for measuring the concentration of a nonionic surfactant, wherein the means for detecting the physical state of the foamed foam is a means for detecting the bulkiness of the generated foam. . According to the present invention, the means for detecting the physical state of the foamed foam is a means for floating a float having a specific gravity of 1 or less in the water in which the foam is generated, and detecting the height of the float. A method for measuring the concentration of a nonionic surfactant is provided. Further, according to the present invention, the concentration of the nonionic surfactant is characterized in that the means for detecting the physical state of the foamed foam is a means for collecting generated foam and detecting its weight. A measuring method is provided. Furthermore, there is provided a method for measuring the concentration of a nonionic surfactant, wherein the means for detecting the physical state of the foamed foam is a means for detecting the light transmittance of a system in which the foam is generated. Is done.

Hereinafter, the present invention will be described in more detail. The concentration measuring method according to claim 1, wherein the method for detecting the concentration of the nonionic surfactant in the water is such that the concentration of the nonionic surfactant in the water is lower than the critical micelle concentration,
Further, air is blown into the water to cause foaming, and the foamed foam is used to detect the concentration of the nonionic surfactant.

Generally, when a surfactant is contained in water,
It is known that the concentration is less than the critical micelle concentration specific to each surfactant, the foaming power rapidly increases, but in the case of surfactants other than soap or nonionic surfactant, other The foaming power greatly changes due to the incorporation of unduly-goods such as fats and oils, mineral components and alcohol components. However, according to the study of the present inventors, in the case of a nonionic surfactant, its foaming power is less affected by other unduly substances, and its foaming power is uniquely determined by the concentration of the nonionic surfactant. It turned out to be decided.

That is, the present invention utilizes the above-mentioned properties of the nonionic surfactant, and dilutes the nonionic surfactant in water so that the concentration of the nonionic surfactant becomes equal to or lower than the critical micelle concentration. The foam is easily foamed by sending air into the foam, and the concentration of the nonionic surfactant is detected based on the foamed foam. The dilution ratio can be any ratio as long as the concentration after dilution is equal to or less than the critical micelle concentration,
For example, a nonionic surfactant having a critical micelle concentration of 50% can have a dilution ratio of 2 or more. If the concentration before dilution is already below the critical micelle concentration,
Needless to say, there is no need for dilution.

[0009] As a method of sending air into water, a method of directly sending air compressed by a compressor, a blower or the like into water, a method of entraining and mixing air into the suction side of a pump, and a method of temporarily adding water containing surfactant to a pressurized tank. A method of dissolving the air in the air and then releasing the air to foam. Also, the size of the air bubbles
The smaller the size is, the better the detection accuracy is, and preferably a bubble having a diameter of 10 mm or less under the atmospheric pressure condition. The detection sensitivity is better if the temperature of the surfactant-containing water is kept constant. The amount of foam generated can be easily grasped visually and the amount of foaming can be easily grasped.For example, as in fixed-point observation of wastewater treatment equipment, it is easy to know the increase or decrease in the concentration of nonionic surfactant by comparing with the amount of foaming before. it can.

A concentration measuring method according to a second aspect is characterized in that, instead of the means for foaming by sending air into water according to the first aspect, foaming is performed by applying vibration to water. Once foamed by the nonionic surfactant, once foamed, it is highly persistent and hardly breaks due to vibration. That is, when conditions such as vibration frequency, acceleration, amplitude, and shaking time are constant, the foaming power is uniquely determined by the surfactant concentration. Examples of the method of applying vibration include a method in which surfactant-containing water and air are put into a container at a fixed ratio and shaking vigorously, a method in which ultrasonic vibration is applied to the surfactant-containing water to cause cavitation, and the like. is there.

According to a third aspect of the present invention, there is provided a method for detecting the concentration of a nonionic surfactant in water, the method comprising measuring the size (diameter) of the foam generated as described above. Is characterized by detecting the concentration of
The higher the concentration of the nonionic surfactant foam, the larger the size (diameter) of the foam. That is, by measuring the size of the foam, the surfactant concentration is uniquely determined.

According to a fourth aspect of the present invention, there is provided a method for detecting the concentration of a nonionic surfactant in water, wherein the concentration of the nonionic surfactant is detected based on the bulk of bubbles generated. And The higher the concentration of the nonionic surfactant foam, the higher the persistence. At this time, the balance between the amount of foam generated per unit time and the amount of foam broken by gravity is the bulk of the foam, that is, the surfactant concentration is uniquely determined by measuring the bulk. As a method of measuring the bulkiness, there are a method of measuring the distance from the water surface by setting the scale in a vertical direction, and a method of measuring the volume by scooping bubbles from the water surface. This measuring method is particularly effective for measuring high-concentration water, and is desirably effective for those having a surfactant concentration of 10 ppm or more.

According to a fifth aspect of the present invention, there is provided a method for detecting the concentration of a nonionic surfactant in water, wherein a float having a specific gravity of 1 or less is floated on water in which bubbles are generated, and a height of the float is determined. And detecting the concentration of the nonionic surfactant. As for the bubbles generated by the nonionic surfactant, when the concentration of the nonionic surfactant is lower than the critical micelle concentration, the higher the density of the nonionic surfactant, the higher the density of the generated bubbles. Further, the density of the generated bubbles is high near the water surface, and the density decreases toward the top. At this time, when a float having a specific gravity of 1 or less floats on the water in which bubbles are generated, the float stops at the height of the foam corresponding to the specific gravity of the float, and by measuring the height of the float, the nonionic surfactant of the nonionic surfactant is measured. The concentration can be detected. In this measurement method,
Compared with the third aspect of the invention in which the bulk of the foam is directly measured, this method is effective when the uppermost part of the foam is difficult to recognize, or when an error due to the sedimentation time of the foam which is generated when the concentration of the surfactant is low tends to occur. The present measuring method is particularly effective for measuring high-concentration water, and is desirably effective for those having a surfactant concentration of 10 ppm or more.

According to a sixth aspect of the present invention, there is provided a method for detecting the concentration of a nonionic surfactant in water, wherein a generated foam is collected and its weight is used to detect the concentration of the nonionic surfactant. It is characterized by doing. Since the volume of the generated bubbles changes with time, an accurate concentration can be detected by measuring the generated bubbles by weight. As a method of measuring the weight of the generated foam, a method of directly weighing the foam as it is or partially liquefying with a foaming device, and then directly measuring the weight with a measuring device such as a precision balance, or a method of vibrating the foam or liquid. In addition, there is a method of measuring the specific gravity and flow rate of the foam based on the natural frequency of the foam and measuring the weight. This measurement method also
It is particularly effective for measuring high-concentration water, and is desirably effective for those having a surfactant concentration of 10 ppm or more.

According to a seventh aspect of the present invention, there is provided a method for detecting the concentration of a nonionic surfactant in water, the method comprising: applying a light beam to water in which bubbles are generated; Detecting, and detecting the concentration of the nonionic surfactant based on the light transmittance. The higher the concentration of the nonionic surfactant-containing water, the greater the amount of microbubbles generated in the liquid and the higher the sustainability. At this time, a light beam is incident on the water in which bubbles are generated, the light beam is detected after transmitting through the water, and the concentration of the ionic surfactant can be detected by measuring the light transmittance. Incident light rays include infrared light, ultraviolet light, visible light, and the like, and can be used after being separated according to wavelength. This measurement method is particularly effective for measuring a low-concentration nonionic surfactant, and is desirably effective for those having a surfactant concentration of 5 ppm or less.

Specific examples of the nonionic surfactant to be measured in the above invention include polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene stearyl ether. Polyoxyethylene alkyl ethers such as oxyethylene oleyl ether,
Single chain polyoxyethylene alkyl ether, polyoxyethylene secondary alcohol ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene glycol alkyl phenyl ether, polyoxyethylene sterol ether, polyoxyethylene lanolin derivative, alkylphenol formalin condensate Ethylene oxide derivative, polyoxyethylene polyoxypropylene block polymer, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene glycerin fatty acid ester, polyoxyethylene castor oil and hydrogenated castor oil, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol Fatty acid ester, polyethylene glycol fatty acid ester, fatty acid monoglyceride, poly Lyserin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, sucrose fatty acid ester, fatty acid alkanolamide, polyoxyethylene fatty acid amide, polyoxyethylene alkylamide, alkylamine oxide, fluorine-based nonionic surfactant, etc. Each of them can be used alone or in combination of one or more.

The nonionic surfactants to be measured in the present invention include other known washing additives such as synthetic zeolites, carbonates, silicates, phosphates, sulfates, and citric acid. Salt, nitrilotriacetate, glyconate,
Glycolate, ammonium salt, EDTA, benzotriazole, nitrite, self-emulsifying silicone, propylenoxide ethylenoxide block polymer, other hydrocarbons, alcohols, ethers, acetals, esters, ketones, amines , Amides, aminoethanols, benzotriazoles, fatty acids, nitroalkanes, anionic surfactants, cationic surfactants,
Soap and the like may be appropriately blended.

[0018]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[Example 1] In FIG. 1, surfactant-containing water 2 is sent to a tank 1 by a pump 3. At this time, the flow rate is measured by a flow meter 4, and the water in the tank is regulated. The dilution water 5 is mixed with the control valve 6 so as to have a dilution ratio. A foamer 7 is provided at the lower part of the tank, and the air compressed by the blower 8 blows out through fine holes opened in the foamer 7. Bubbled foam 10 at the top of the tank
A core rod 9 was set on the surface of the water to make it easy to gather due to surface tension, and the size A of the foam spread on the surface of the water when viewed from above the tank was measured. In this apparatus, the surfactant concentrations after dilution were 10, 100, 1,000, and 1, respectively.
FIG. 7 shows the results of measurement using samples having a concentration of 0000 or 100,000 mg / l.

[Embodiment 2] In FIG. 2, a vibrator 12 was installed on the water surface of the tank in place of the foaming by the foaming device in the embodiment 1, and the impeacher on the water surface was vibrated by the vibrator 13 to foam. Other than that, it carried out similarly to Example 1. This measurement result is also shown in FIG.

[Embodiment 3] In FIG. 3, the surfactant-containing water 1 is sent to the foaming tank 14 by the pump 3.
A foaming device is provided below the foaming tank, and the air compressed by the blower 8 blows out from a fine hole formed in the foaming device 7. A foam storage tank 15 is provided above the foaming tank. The foam overflowing from the foaming tank and the liquid portion 16 are separated by a mesh 17 that allows only the liquid portion to pass therethrough. Only remains in the foam storage tank 15. The bulk B of the foam at this time is measured as the height of the foam from the water surface of the foam tank. In this apparatus, the surfactant concentration is 10, 100, 1,000, 10,
FIG. 8 shows the results of measurement using a sample having a concentration of 000, 100,000 mg / l.

[Embodiment 4] In FIG. 4, instead of measuring the bulkiness of the foam in Embodiment 3, a float 1 having a specific gravity of 0.3 was used.
8 was floated in the foam storage tank, and the procedure was the same as in Example 3 except that the height C of the float was measured as the foam height. This measurement result is also shown in FIG.

[Embodiment 5] In FIG. 5, instead of using the foam storage tank in Embodiment 3, the generated foam was sent to a foam breaker 20 by a foam guide tube 19. As the foam breaker 20, a system based on reduced pressure and centrifugation was used. The weight of the liquefied foam was measured by a weighing scale 21. In this apparatus, the surfactant concentrations were 10, 100, 1,000, 10,
FIG. 9 shows the results of measurement using a sample having a concentration of 000, 100,000 mg / l.

Embodiment 6 In FIG. 6, the surfactant-containing water 2 is once passed through a filter 22 by a pump 3 to remove solids. Next, the vibration generated by the ultrasonic vibrator 23 is added to the surfactant-containing water to cause foaming, and
A light ray (infrared ray) 26 is made incident by 4 and transmitted through the water, and then its transmittance is detected by the light receiver 25. In the present embodiment, a filter 22 having a filtering accuracy of 0.1 μm is used, a vibration frequency is 28 KHz, and an ultrasonic vibrator 23 of 300 w is used. did. In this apparatus, the surfactant concentrations were 0.01, 0.1, 1, 10, 100, respectively.
FIG. 10 shows the result of measurement using a sample having a concentration of mg / l.

[0025]

According to the present invention, the nonionic surfactant in water is diluted so that the concentration thereof is equal to or lower than the critical micelle concentration, and is further foamed by blowing air into the water or applying vibration to the foamed foam. By detecting the physical state and detecting the concentration of the nonionic surfactant (at this time, as means for detecting the physical state of the water containing the bubbles, the size of the generated bubbles, the bulkiness, and the height of the floats are increased. The weight of the system in which the foam is generated or the light transmittance of the system in which the foam is generated is preferable), and the concentration of the nonionic surfactant contained in the wastewater or the like can be easily detected. is there.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is a diagram showing still another embodiment of the present invention.

FIG. 4 is a diagram showing still another embodiment of the present invention.

FIG. 5 is a diagram showing still another embodiment of the present invention.

FIG. 6 is a diagram showing still another embodiment of the present invention.

FIG. 7 is a graph showing the relationship between the surfactant concentration and the size of bubbles in Examples 1 and 2.

FIG. 8 is a graph showing the relationship between surfactant concentration and foam height in Examples 3 and 4.

FIG. 9 is a diagram showing the relationship between the surfactant concentration and the weight of foam in Example 5.

FIG. 10 is a graph showing the relationship between the surfactant concentration and the light transmittance of a liquid containing bubbles in Example 6.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tank 2 Surfactant-containing water 3 Pump 4 Flow meter 5 Dilution water 6 Control valve 7 Foamer 8 Blower 9 Core rod 10 Foam 11 Drain 12 Vibrator 13 Vibrator 14 Foaming tank 15 Foam tank 16 Foam tank 16 Liquid part 17 Mesh 18 Floater 19 Bubble tube 20 Foam breaker 21 Weight scale 22 Filter 23 Ultrasonic vibrator 24 Floodlight 25 Light receiver 26 Ray A Size of foam B Bulk height of foam C Height of float

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-90114 (JP, A) JP-A-4-172230 (JP, A) JP-A-2-138829 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G01N 5/00 G01N 7/00 G01N 13/00 G01N 21/59 JICST file (JOIS)

Claims (7)

(57) [Claims] 1. The method according to claim 1, wherein air is blown into an aqueous phase diluted with water so that the concentration of the nonionic surfactant in the water is equal to or lower than the critical micelle concentration, and foaming is performed, and the physical state of the generated foam is detected. Method for measuring the concentration of a nonionic surfactant. 2. A method of applying a vibration to an aqueous phase diluted with water so that the concentration of the nonionic surfactant in the water is equal to or lower than the critical micelle concentration, foaming the water phase, and detecting a physical state of the generated foam. Method for measuring the concentration of a nonionic surfactant. 3. The nonionic surfactant according to claim 1, wherein the means for detecting the physical state of the foamed foam is a means for detecting the size of the generated foam. Concentration measurement method. 4. The nonionic surfactant according to claim 1, wherein the means for detecting the physical state of the foamed foam is a means for detecting the bulkiness of the generated foam. Concentration measurement method. 5. The means for detecting the physical state of the foamed foam is a means for floating a float having a specific gravity of 1 or less in the water in which the foam is generated, and detecting the height of the float. The method for measuring the concentration of a nonionic surfactant according to claim 1 or 2, wherein 6. The method according to claim 1, wherein the means for detecting the physical state of the foamed foam is a means for sampling the generated foam and detecting its weight. A method for measuring the concentration of a nonionic surfactant. 7. The method according to claim 1, wherein the means for detecting the physical state of the foamed foam is a means for detecting the light transmittance of a system in which the foam is generated. A method for measuring the concentration of a nonionic surfactant.