TW202006352A - Fluorine concentration measurement method, fluorine concentration measurement device, water treatment method, and water treatment device - Google Patents

Abstract

A fluorine concentration measurement method comprising the steps of: measuring the potential of sample water with a fluorine ion electrode meter to obtain a potential value P; bringing the sample water into contact with a fluorine adsorbent agent to produce fluorine-removed sample water; adding a fluorine compound to the fluorine-removed sample water to prepare a first standard solution for a fluorine concentration C1; adding a fluorine compound or not adding a fluorine compound to the fluorine-removed sample water to prepare a second standard solution for a fluorine concentration C2; measuring the potential of the first standard solution with a fluorine ion electrode meter to obtain a potential value P1; measuring the potential of the second standard solution with a fluorine ion electrode meter to obtain a potential value P2; prepare a calibration curve that represents the correlation between a fluorine concentration and a potential value employing the fluorine concentrations C1 and C2 and the potential values P1 and P2; and calculating the fluorine concentration of the sample water which corresponds to the potential value P on the basis of the calibration curve.

Description

Fluorine concentration measurement method, fluorine concentration measurement device, water treatment method and water treatment device

The present invention relates to a fluorine concentration measurement method, a water treatment method using the method, a fluorine concentration measurement device, and a water treatment device including the device.

Methods for measuring the concentration of fluoride ions in a solution using ion selective electrodes are currently known. For example, Non-Patent Document 1 describes the general content of quantifying the ion concentration using an ion electrode, and also describes the following: the ion potential can be measured by using the ion electrode to obtain the fluoride ion concentration, and an ion activity corresponding to the ion activity can be generated at the ion electrode. The membrane potential and activity coefficient are affected by the ionic strength, which causes changes and measurement errors. Sometimes, in order to keep the ionic strength of the sample water constant, a high-concentration electrolyte solution is added as the ionic strength adjustment solution. Because of the influence of coexisting ions, it is necessary to take measures to avoid such influence. Non-Patent Document 2 describes that in order to avoid the influence of coexisting ions in the ion electrode method, the fluorine compound is pretreated, distilled and separated, a buffer solution (ionic strength adjustment solution) is added, and the pH value is adjusted to 5.2±0.2, and fluorine is used The compound ion selective electrode measures the potential to quantify the fluoride compound ion. Non-Patent Document 3 describes that in order to prevent the influence of the complex caused by the coexisting ions of fluorine compound ions in the ion electrode method, sodium citrate or cyclohexanediaminetetraacetic acid can be added to suppress the fluorine compound ions and Fe or Al produces a complex reaction. Patent Document 1 discloses a method in which the ion electrode can be used to measure the fluorine concentration in the sample water when the ion electrode method is used to reduce the influence of coexisting magnesium ions. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2011-47768 [Non-patent literature]

[Non-Patent Document 1] Japanese Industrial Standard JIS K 0122-1997 [Non-Patent Document 2] Japanese Industrial Standard JIS K 0102-2016 [Non-Patent Document 3] Yamada et al., "Simple Quantification of Fluoride Ions in Wastewater by Ion Electrode Method", Analytical Chemistry, Vol. 37, T61 to T65 (1988)

[Problems to be solved by the invention]

As described above, when measuring the fluorine concentration using a fluoride ion meter, it may be difficult to measure the precise fluorine concentration due to the influence of coexisting ions, or the pretreatment may be complicated. Furthermore, in the method of diluting sample water with water as described in Patent Document 1, when the amount of coexisting magnesium ions is greater than the amount of fluoride ions, it is necessary to set a higher dilution rate, so the quantification of the fluorine concentration The lower limit value inevitably rises, and it becomes difficult to measure accurate fluorine concentration for sample water with low fluorine concentration, which limits the application range.

The present invention has been completed in view of the foregoing circumstances, and an object thereof is to provide a fluorine concentration measurement method and a fluorine concentration measurement device that can easily and accurately determine or calculate the fluorine concentration in a sample water even in a sample water containing coexisting ions. Furthermore, the present invention also provides a water treatment method using the fluorine concentration measurement method of the invention, and a water treatment device including the fluorine concentration measurement device of the invention. [Means for solving problems]

The fluorine concentration measuring method of the present invention capable of solving the foregoing problems includes the following steps: measuring the potential of the sample water with a fluoride ion electrode to obtain a potential value P; contacting the sample water with a fluorine adsorbent to obtain a defluorinated sample The step of water; the step of adding a fluorine compound to the sample water of fluoride removal to prepare a reference solution with a fluorine concentration of C1; the step of measuring the potential of the reference solution using a fluoride ion electrode meter to obtain the potential value P1; the potential value P and The step of comparing the potential value P1 to determine the magnitude relationship between the fluorine concentration of the sample water and the fluorine concentration C1. The fluorine concentration measuring method of the present invention may also be a method including the steps of: measuring the potential of the sample water using a fluoride ion electrode meter to obtain the potential value P; contacting the sample water with a fluorine adsorbent to obtain the defluorinated sample water The steps of adding fluorine compounds in the fluoride sample water to prepare the first reference solution of fluorine concentration C1; adding or not adding fluoride compounds in the sample water of fluoride removal to prepare the second reference of fluorine concentration C2 The steps of the solution; the step of measuring the potential of the first reference solution using a fluoride ion electrode meter to obtain the potential value P1; the step of measuring the potential of the second reference solution using a fluoride ion electrode meter to obtain the potential value P2; using the fluorine concentration C1 , C2 and the potential values P1 and P2, a step of creating a calibration curve showing the correlation between the fluorine concentration and the potential value; based on the calibration curve, the step of calculating the fluorine concentration of the sample water corresponding to the potential value P.

According to the fluorine concentration measuring method of the present invention, the sample water and the fluorine adsorbent are contacted to prepare a sample water except for fluorine, and a fluorine compound is added to prepare a reference solution, so the sample water and the reference solution have substantially the same except for the fluorine component. Composition (matrix). Therefore, the sample water and the reference solution are compared and measured between solutions with the same matrix, and the potential measurement is basically only a function of the fluorine concentration. According to this, according to the fluorine concentration measuring method of the present invention, even if a large amount of coexisting ions exist in the sample water, a reference solution corresponding to the sample water can be used to create an accurate calibration curve. Furthermore, since the fluoride ion meter is used for potential measurement, simple and fast measurement can be performed.

In the step of formulating the reference solution, it is better to use a fluorine standard solution of known fluorine concentration as the fluorine compound added to the fluorine-removing sample water. In this way, the reference solution of the desired fluorine concentration can be easily prepared.

In the step of obtaining the potential value P, the fluoride standard solution after contacting the fluorine standard solution with the fluorine adsorbent may also be added to the sample water, and the potential of the resulting solution may be measured with a fluoride ion electrode meter.

The ionic strength of the sample water is preferably 0.05 mol/L to 3.5 mol/L. According to the present invention, even the sample water having such ionic strength can accurately measure the fluoride ion concentration. As the sample water, for example, flue gas desulfurization wastewater discharged from the flue gas desulfurization equipment can be used.

The invention also provides a fluorine concentration measuring device. The fluorine concentration measuring apparatus according to the present invention includes: a measurement section including a fluoride ion electrode meter, a first supply unit that supplies sample water to the measurement section, a fluorine removal section provided with a fluorine adsorbent, and a first section that supplies sample water to the fluorine removal section 2 Supply unit, a fluorine compound supply unit that adds a fluorine compound to the fluorine removal sample water discharged from the fluorine removal unit to obtain a reference solution, a third supply unit that supplies the fluorine removal sample water or the reference solution to the measurement unit, and the use measurement unit A calculation unit that calculates the value or magnitude relationship of the fluorine concentration in the sample water from the measured potential values of the sample water and the reference solution. If the fluorine concentration measuring device of the present invention is used, the fluorine concentration in the sample water can be easily or accurately determined or calculated.

The fluorine concentration measuring device may further include a mixing unit that mixes the fluorine removal sample water discharged from the fluorine removal unit and the fluorine compound supplied from the fluorine compound supply unit to prepare a reference solution. The mixing section may be provided in a pipeline communicating with the outlet side of the fluorine removal section.

The fluorine concentration measuring device may be provided with a first measuring section for analyzing sample water and a second measuring section for analyzing reference solution as the measuring section. In this case, the first supply unit supplies the sample water to the first measurement unit, and the third supply unit supplies the defluorinated sample water or the reference solution to the second measurement unit. If the first measurement section for analyzing the sample water and the second measurement section for analyzing the reference solution are provided as described above, the fluorine concentration of the sample water can be determined or calculated more quickly.

The fluorine concentration measuring device further includes a water intake part that receives the sample water, a first supply line provided with the inlet side of the water intake part and the measurement part as the first supply unit, and an inlet connected with the water intake part and the fluorine removal part The second supply line communicating on the side is preferably the aforementioned second supply unit. By setting the water taking part in this way, the sample water and the reference solution can be exactly the same source.

As the fluorine compound, it is preferable to use a fluorine standard solution of known fluorine concentration. In this case, the fluorine concentration measuring device may further include a second fluorine removal unit provided with a fluorine adsorbent and supplying a fluorine standard solution, and supplying the fluorine removal standard solution discharged from the second fluorine removal unit to the measurement unit The fourth supply unit.

The present invention further provides a water treatment method incorporating the fluorine concentration determination method of the present invention. The water treatment method of the present invention is, for example, a method of removing at least a part of fluoride ions from water containing fluoride ions to obtain treated water, and using the fluorine concentration measurement method of the present invention to treat the treated water as sample water. Measure the fluorine concentration in the treated water. The water treatment method of the present invention is a water treatment method in which chemicals are added from water containing fluoride ions to remove at least a part of fluoride ions. Using the fluorine concentration measurement method of the present invention, water containing fluoride ions is used as a sample water to measure the content of fluorine. Fluorine concentration in ionized water, and based on this measurement, determine the amount of chemicals added to the water containing fluoride ion. The water treatment method of the present invention is a water treatment method that introduces water containing fluorine ions into a fluorine adsorption tower filled with a fluorine adsorbent to remove at least a part of the fluoride ions. Water is used as the sample water, and the fluorine concentration in the water containing fluoride ions is measured, and based on the measurement result, the fluoride ion water is diluted.

The present invention further provides a water treatment device, which is a water treatment device that removes at least a part of fluoride ions from water containing fluoride ions to obtain treated water, and includes the fluorine concentration measurement device of the present invention. [Effect of invention]

According to the fluorine concentration measurement method and the fluorine concentration measurement device of the present invention, even if the sample water contains a large amount of coexisting ions, the fluoride ion concentration in the sample water can be easily or accurately determined or calculated.

The fluorine concentration measuring method of the present invention will be described with reference to FIG. 1. FIG. 1 is a flowchart showing the method for measuring the fluorine concentration of the present invention. The method for determining the fluorine concentration of the present invention includes the following steps: a step of measuring the potential of the sample water using a fluoride ion electrode to obtain a potential value P (sample water measurement step); contacting the sample water with a fluorine adsorbent to obtain fluorine removal The step of sample water (defluorination step); the step of adding a fluorine compound to the aforementioned defluoridation sample water to prepare a reference solution with a clear fluorine concentration (reference solution preparation step); using a fluoride ion electrode meter to measure the The step of obtaining the potential P1 (reference solution measurement step); the step of determining or calculating the fluorine concentration of the sample water from the measured values of the potential values measured in the sample water measurement step and the reference solution measurement step ( Fluorine concentration judgment/calculation procedure). According to the fluorine concentration measuring method of the present invention, the fluoride ion concentration in the sample water can be obtained simply and accurately. In addition, in this specification, "fluoride ion" has the same meaning as "fluoride ion", and "fluorine concentration" means "fluorine ion concentration".

The type of sample water used for measurement is not particularly limited, and may be sample water containing fluoride ions, or sample water not containing fluoride ions. For example, when wastewater from various industries such as industry, agriculture, and fishery, process wastewater, household wastewater, etc. is used as the sample water, the sample water may contain fluoride ions. Conversely, when the treated water is used as the sample water, the sample water may not contain fluoride ions. Furthermore, water in a natural environment such as river water, lake water, ground water, sea water, etc. may be used as the sample water.

The sample water is also allowed to contain components other than fluoride ions, and can also contain any coexisting ions of any content. When measuring the concentration of fluoride ions using a fluoride ion electrode meter, the potential value is usually changed due to the influence of coexisting ions, or the coexisting ions produce inhibitors during the detection of fluoride ions, so it becomes necessary to consider these Coexisting ions. For example, since the potential value measured with a fluoride ion meter is affected by the ionic strength in the sample water, it becomes necessary to add an ionic strength adjuster (a strong electrolyte salt unrelated to ion measurement) to suppress this effect. Furthermore, in the case where the sample water contains a large amount of metal components such as magnesium ions, aluminum ions, iron ions, calcium ions, etc., fluoride ions react with these metal components, resulting in a decrease in the measured value of the fluoride ion meter. Therefore, it becomes necessary to add chemicals for inhibiting the complexation reaction of fluoride ions. However, in the present invention, even if the sample water contains the above-mentioned coexisting ions, and even if there are coexisting ions in the sample water that affect the measurement of the fluoride ion electrode meter, the fluoride ion concentration in the sample water can be accurately determined.

For example, in coal-fired thermal power plants, coking plants, steel plants, etc., exhaust gas containing sulfur and fluorine components is emitted by burning coal or coke, when this exhaust gas is desulfurized by flue gas desulfurization equipment , Will produce flue gas desulfurization wastewater containing high concentrations of fluoride ions and sulfate ions. As a desulfurization method for flue gas desulfurization equipment, a method of wet treatment using magnesium hydroxide, sodium hydroxide, or calcium hydroxide is known. However, when these metal hydroxides are used as a desulfurization agent, a high content of Flue gas, fluoride ion, sulfate ion and metal ion (magnesium ion, sodium ion and calcium ion) flue gas treatment wastewater. Generally, it is difficult to measure the fluorine concentration in this flue gas treatment wastewater using a fluoride ion electrode meter. However, according to the present invention, the flue gas desulfurization wastewater discharged from the flue gas desulfurization equipment can also be accurately used as sample water. The fluorine concentration in this wastewater is measured. In addition, as waste water containing coexisting ions and fluoride ions that affect the measurement value of the fluoride ion electrode meter, scrubber waste water discharged from an optical fiber manufacturing machine and the like can also be mentioned. According to the present invention, the waste water of the scrubber can be used as the sample water to accurately measure the fluorine concentration.

The ionic strength of the sample water to be measured is not particularly limited. Conventionally, when a large amount of a metal component capable of complexing with fluoride ions is contained, it is difficult to measure the fluoride concentration using a fluoride ion electrode meter. However, according to the present invention, it becomes possible to measure the fluoride ion concentration of such sample water. Therefore, from such a viewpoint, the ionic strength of the sample water may be, for example, 0.05 mol/L to 3.5 mol/L. Of course, in the present invention, the fluorine concentration of the sample water having a lower ionic strength or a higher ionic strength than the above can also be measured.

It is also possible to adjust the pH value of the sample water according to the requirements before the sample water measurement step and the defluorination step. The pH value of the sample water is preferably 2.0 or more, preferably 2.5 or more, more preferably 2.8 or more, and preferably 7.0 or less, preferably 6.0 or less, 5.0 or less, and 4.0 or less For better. If the pH value of the sample water is within such a range, the fluoride ion in the sample water becomes easy to exist in a free state, and the fluoride ion becomes easily adsorbed and removed by the adsorbent in the defluorination step. Therefore, when the pH of the sample water is outside the above range, it is better to adjust the pH to within the above range by adding acid or alkali.

It is also possible to dilute the sample water with water according to the requirements before the sample water measurement step and the defluorination step. For example, when the pH of the sample water is extremely high or extremely low, or when the concentration of coexisting ions in the sample water is extremely high, the sample water may be appropriately diluted with water. For example, in the case where the concentration of coexisting ions in the sample water is extremely high, when the sample water is contacted with the fluorine adsorbent in the defluorination step, the adsorption and removal of fluoride ions takes a long time, or fluorine may occur The ions are not sufficiently removed, so it can also be diluted with water to speed up the defluorination step. In addition, even if the sample water is diluted with water, it is preferable to suppress the dilution rate as much as possible, whereby it becomes possible to quantify the sample water having a lower fluorine concentration. Therefore, in the case of diluting the sample water with water, it is not necessary to dilute it to the extent that, for example, the metal component and the fluoride ion generating the complexation reaction are free.

In the sample water measurement step, the potential of the sample water is measured using a fluoride ion electrode meter to obtain the potential value P. As the fluoride ion electrode meter, a known fluoride ion electrode meter may be used, and a fluoride ion electrode meter provided with a fluoride ion electrode may be used, wherein the fluoride ion electrode generates a potential corresponding to the concentration (activity) of the fluoride ion in the solution. By measuring the electromotive force of a battery composed of a membrane electrode combined with a fluoride ion selective membrane and a comparative electrode (reference electrode), the potential value corresponding to the fluoride ion concentration (activity) in the solution can be obtained. For example, when a fluoride ion electrode meter is connected to an ion densitometer, the measured potential value P can be displayed or stored in the ion densitometer.

The potential value P obtained in the sample water measurement step is a value affected by the coexisting ions in the sample water. Therefore, this potential value P cannot be directly converted into the fluorine concentration value in the sample water. Therefore, in the present invention, the reference solution is additionally prepared through the defluorination step and the reference solution preparation step, the potential value of the reference solution is measured in the reference solution measurement step, and in the fluorine concentration judgment/calculation step The potential value P is compared to obtain the fluorine concentration of the sample water.

In the defluorination step, the sample water from the same source as in the measurement of the potential value P is brought into contact with the fluorine adsorbent to obtain the defluorinated sample water. The sample water used in the defluorination step may be the same batch as the sample water used in the sample water measurement step, or may be a different batch. In the former case, for example, a part of the sample water collected in one batch is used for the sample water measurement step, and the other part is used for the fluorine removal step. Alternatively, the sample water whose potential is measured in the sample water measurement step may be used in the fluorine removal step. In the latter case, for example, the sample water used for the defluorination step may be collected after the sample water used for the sample water measurement step is collected, or the reverse order may also be used. Basically, it would be desirable to collect samples for the sample water measurement step at as close a time difference as possible (eg, within 30 minutes is preferred, within 15 minutes is preferred, and within 10 minutes is preferred) Water and the sample water used in the defluorination step, however, in the case where the composition of the sample water changes little with time, the above-mentioned time difference may also have a certain range.

As the fluorine adsorbent, any known adsorbent capable of adsorbing fluoride ions can be used, for example, an alumina-based adsorbent, a ferrite iron-based adsorbent, a zirconium-based adsorbent, a cerium-based adsorbent, and the like can be used. Among them, it is preferable to use a zirconium-based adsorbent or a cerium-based adsorbent as an adsorbent that can adsorb and remove fluoride ions to a high degree. Examples of the zirconium-based adsorbent include an adsorbent containing zirconia (ZrO ₂ ), particularly hydrous zirconia (ZrO ₂ ·nH ₂ O). Examples of the cerium-based adsorbent include an adsorbent containing cerium oxide (CeO ₂ ), particularly an adsorbent containing hydrous cerium oxide (CeO ₂ ·nH ₂ O). These adsorbents may also contain resins to fix or reinforce zirconia, cerium oxide, etc. with the resin.

The contact between the sample water and the fluorine adsorbent can be carried out in the bath, or it can be carried out by the liquid flowing through the adsorption tower. For example, in the case where the sample water is in contact with the fluorine adsorbent in the bath, the fluorine adsorbent can be added to the sample water still in the bath. At this time, the fluorine adsorbent may be directly contacted with the sample water in this state, or a bag into which the fluorine adsorbent can flow through may be immersed in the sample water, or the fluorine adsorbent formed into a predetermined shape Immerse in the sample water to treat the fluorine adsorbent as a whole. The addition amount of the fluorine adsorbent at this time can be appropriately set within a range of 1 g/L to 100 g/L with respect to 1 L of sample water, for example. The amount of fluorine adsorbent added can be appropriately set according to the expected fluorine concentration of the sample water, and even if the fluoride ion in the sample water fluctuates within the expected range, the fluoride ion set to more than 95% can be adsorbed within 3 minutes and The amount of addition is better. Of course, it may be an amount of adsorbent that can achieve a high adsorption rate in a shorter time than the above. From the viewpoint of rapid measurement of fluorine concentration, the contact time between the sample water and the fluorine adsorbent is preferably set appropriately between 15 seconds and 10 minutes (preferably between 30 seconds and 5 minutes) ).

In the case where the sample water is in contact with the fluorine adsorbent in the adsorption tower, the sample water can flow through the adsorption tower filled with the fluorine adsorbent. The sample water can flow upwards through the adsorption tower, it can also flow downwards, or it can flow laterally. In these cases, the adsorbent can be filled in the pipeline to serve as an adsorption tower. The filling amount of the fluorine adsorbent filled in the adsorption tower is, for example, an amount where more than 95% of fluoride ions are adsorbed and removed when the sample water passes at a space velocity (SV) of 20 hr ^-1 . Of course, it may be an amount of adsorbent that can achieve a high adsorption rate at a faster space velocity than the above. The liquid flow rate of the sample water in the adsorption tower, for example, it is better to set the space velocity (SV) appropriately within the range of 6 hr ^-1 to 180 hr ^{-1 (} in the range of 12 hr ^-1 to 120 hr ^-1 Within the range is better).

In the defluorination step, by contacting the sample water with a fluorine adsorbent, the defluorinated sample water from which fluoride ions have been removed from the sample water is obtained. In addition, the fluoride ion concentration of the defluorinated sample water may not be completely 0 mg/L. The fluoride ion concentration of the defluorinated sample water is, for example, preferably 3 mg/L or less, preferably 2 mg/L or less, more preferably 1 mg/L or less, and particularly preferably 0.5 mg/L or less. Alternatively, the fluoride ion removal rate in the fluorine removal step is preferably 95% or more, preferably 97% or more, and more preferably 99% or more. Basically, when determining the fluorine concentration of the sample water, the fluoride ion concentration of the defluorinated sample water can be reduced to a level where sufficient accuracy can be obtained (for example, the error is within ±5%).

The fluorine-removed sample water obtained in the fluorine-removal step is then added with a fluorine compound in the reference solution preparation step to prepare a reference solution. The type of fluorine compound added when formulating the reference solution is not particularly limited, but from the viewpoint of excellent solubility in water and easy availability, alkali metal salts of fluorine are preferred, and sodium fluoride is preferred good. Fluorine compounds can be added to the defluorinated sample water as a solid, or can be added to the defluorinated sample water as a solution. In addition, the fluorine compound is preferably added as a solution to the defluorinated sample water, so that a reference solution in which fluoride ions are dissolved at a predetermined concentration can be easily prepared. The addition amount of the fluorine compound solution at this time is preferably 3 parts by mass or less, preferably 2 parts by mass or less, and more preferably 1 part by mass or less with respect to 100 parts by mass of the defluorinated water sample. That is, it is preferable to appropriately adjust the fluorine concentration of the fluorine compound solution to achieve the above-mentioned addition amount.

In the reference solution preparation step, it is preferable to prepare a fluorine compound solution of a predetermined concentration in advance, and adjust the addition amount of the fluorine compound solution according to the fluorine concentration of the reference solution, so that it becomes possible to easily prepare a compound having a desired fluorine concentration Reference solution. As such a fluorine compound solution, it is convenient to use a fluorine standard solution having a known fluorine concentration. The fluorine compound solution or fluorine standard solution may contain a pH buffering agent and the like.

In the reference solution preparation step, a reference solution having a fluorine concentration C1 is prepared. The fluorine concentration C1 of the reference solution is used to determine the relationship between the fluorine concentration of the sample water and the fluorine concentration of the sample water, for example, it can be set as the reference fluorine concentration of the sample water (for example, the discharge standard value set by the Ministry of Environment, In the treatment of fluorine concentration, the upper limit value of the fluorine concentration in the specifications of the processing equipment, or the value obtained by multiplying the safety factor by these values). The fluorine concentration C1 of the reference solution is set to the value obtained by dividing the fluorine concentration of the added fluorine compound, that is, the amount (mass or molar amount) of the added fluorine compound F by the volume of the reference solution. .

In the reference solution preparation step, the second reference solution having the fluorine concentration C2 may be prepared at the same time as the first reference solution having the fluorine concentration C1. The fluorine concentration C1 of the first reference solution and the fluorine concentration C2 of the second reference solution can be set, for example, as the reference fluorine concentration of the sample water, or can be appropriately set to a fluorine concentration suitable for creating a calibration curve. The second reference solution may be a reference solution adjusted to a fluorine concentration C2 by adding a fluorine compound to the defluorinated sample water, or it may be adjusted to a fluorine concentration C2 by not adding a fluorine compound to the defluorinated sample water Reference solution. In the latter case, the fluorine concentration of the second reference solution is 0 mg/L or a value close to 0 mg/L (for example, 1 mg/L). In the reference solution preparation step, a third reference solution having a fluorine concentration C3 or a fourth reference solution having a fluorine concentration C4 may be further prepared.

The pH value of the reference solution obtained in the reference solution preparation step is preferably 2.0 or more, preferably 2.5 or more, more preferably 2.8 or more, and preferably 7.0 or less, preferably 6.0 or less, 5.0 The following is better, and 4.0 or less is even better. In the case where the pH value of the reference solution is outside the above range, it is better to adjust the pH value to within the above range by adding acid or alkali to the reference solution or the defluorinated sample water. The difference between the pH value of the reference solution that measures the potential value using the fluoride ion electrode and the pH value of the sample water that measures the potential value using the fluoride ion electrode is not too great. The difference between the two is preferably within 2.0 , Within 1.5 is better, and within 1.0 is better.

In addition, in the reference solution preparation step, the fluorine compound is added to the defluorinated sample water to prepare the reference solution. However, in the reference solution thus obtained, the cation component from the fluorine compound exists in the form of being added to the original sample water. Therefore, from the viewpoint that the ionic strength and coexisting ionic components of the sample water and the reference solution are very complete, it is also possible to add the hydroxide of the cation of the fluorine compound added to the defluorinated sample water to the sample water before the sample water measurement step . The amount of the hydroxide of the cation added at this time is preferably the amount corresponding to the cation of the fluorine compound added to the defluorinated sample water. In the case where the pH buffer is added in the reference solution preparation step, the same amount of pH buffer may also be added to the sample water before the sample water measurement step. When the fluorine compound solution (for example, fluorine standard solution) is added to the defluorinated sample water, the fluorine compound solution (for example, fluorine standard solution) that is in contact with the fluorine adsorbent can also be added to the sample water and measured by a fluoride ion electrode meter. The potential of the obtained solution is used to obtain the potential value P. In this case, a fluoride compound solution from which fluoride ions have been removed or a fluoride standard solution from which fluoride ions have been removed (for example, a standard solution for removing fluoride) is added to the sample water. In addition, even if the ionic strength and coexisting ionic components of the sample water and the reference solution are not very complete, the fluorine concentration of the sample water can usually be measured with high enough accuracy.

After the reference solution preparation step, in the reference solution measurement step, the potential of the reference solution is measured using a fluoride ion electrode meter. In the reference solution measurement step, a fluoride ion electrode meter may be used to measure the potential of the reference solution in the same manner as the sample water measurement step described above. The fluoride ion meter used to measure the reference solution may be the same as the fluoride ion meter used to measure the sample water, or it may be different. In the reference solution measurement step, the potential value P1 is obtained as the potential value of the (first) reference solution having the fluorine concentration C1. When the second reference solution having the fluorine concentration C2 is prepared in the reference solution preparation step, the potential value P2 is obtained as the potential value of the second reference solution in the reference solution measurement step. Similarly, in the case where the third reference solution having the fluorine concentration C3 and the fourth reference solution having the fluorine concentration C4 are prepared in the reference solution preparation step, the potential value P3 is obtained as the potential of the third reference solution in the reference solution measurement step Value, and the potential value P4 is obtained as the potential value of the fourth reference solution.

Next, in the fluorine concentration judgment/calculation step, the fluorine concentration of the sample water is judged or calculated based on the measured values of the potential values obtained from the sample water measurement step and the reference solution measurement step. When determining the fluorine concentration of the sample water, compare the potential value P of the sample water with the potential value P1 of the (first) reference solution having the fluorine concentration C1, and determine the magnitude of the fluorine concentration of the sample water to the fluorine concentration C1 relationship. At this time, if the potential value P is much larger than the potential value P1, it can be judged that the fluorine concentration of the sample water is much smaller than C1, and if the potential value P is much smaller than the potential value P1, it can be judged that the fluorine concentration of the sample water is much larger than C1. The relationship between the fluorine concentration C2 of the second reference solution, the fluorine concentration C3 of the third reference solution, and the fluorine concentration C4 of the fourth reference solution may also be determined.

When calculating the specific value of the fluorine concentration of the sample water, before the fluorine concentration determination/calculation step, the correlation between the fluorine concentration and the potential value is created based on the fluorine concentration C1, C2 and the potential values P1, P2 The calibration curve steps (calibration curve production steps). When creating the calibration curve, set the horizontal axis as the potential value and the vertical axis as the logarithm value of the fluorine concentration, and plot the fluorine concentration C1 and the potential value P1 of the first reference solution and the fluorine concentration C2 and the second reference solution. The potential value P2 is linearly approximated to create a calibration curve. From the viewpoint of producing a more accurate calibration curve, it is better to further plot the fluorine concentration C3 and potential value P3 of the third reference solution, and to further plot the fluorine concentration C4 and potential value P4 of the fourth reference solution. good.

FIG. 2 is a graph showing the calibration curve prepared in the above manner, and a graph showing the relationship between the potential value and the fluorine concentration of the measurement results of sample water with various fluorine concentrations. First, prepare 5 kinds of reference solutions with MgSO ₄ concentration of 60,000mg/L, pH value of 5.4, and fluorine concentration of 1mg/L, 10mg/L, 25mg/L, 50mg/L, 100mg/L, and measure each The potential value is drawn, and the relationship between the potential value and the fluorine concentration (logarithmic value) is drawn to make a calibration curve. Next, sample water having an MgSO ₄ concentration of 60,000 mg/L, a pH value of 5.4, and an arbitrary fluorine concentration was prepared, and the relationship between the potential value and the measured value of the fluorine concentration was plotted. As shown in Figure 2, the calibration curve shows a good linearity in the relationship between the potential value and the fluorine concentration (logarithmic value), and it can be seen that the measured value of the sample water of any fluorine concentration is also located on this calibration curve.

According to the fluorine concentration measuring method of the present invention, the fluoride ion is removed from the sample water to prepare a defluorinated sample water, and a fluorine compound is added to prepare a reference solution, so the sample water and the reference solution have substantially the same except for the fluorine component Composition (matrix). That is, the type and concentration of the coexisting ions contained in the sample water and the reference solution, except for the presence of fluoride ions, are almost the same, and the ionic strength is the same except for the fluorine component. Even if there is a component in the sample water and reference solution that may react with fluoride ion, this component has the same kind and concentration in the sample water and reference solution, so the degree of influence of this component on the fluoride ion is also identical. Therefore, the sample water and the reference solution are compared/measured between solutions with the same matrix, and the potential measurement is basically only a function of the fluorine concentration. Therefore, according to the fluorine concentration measurement method of the present invention, even if a large amount of coexisting ions exist in the sample water, a reference solution corresponding to the sample water can be used to make an accurate calibration curve or to judge the size relationship. In addition, since the fluoride ion meter is used for potential measurement, simple and fast measurement can be performed.

The present inventor has studied the effect of coexisting ions on the measured value of fluorine concentration. For example, for two solutions with the same fluoride ion concentration, one of them contains no magnesium sulfate at all, while the other contains 60,000 mg/L For magnesium sulfate, the fluorine concentration is measured using a fluoride ion electrode meter. The fluorine concentration of the solution containing magnesium sulfate is about 1/10 of the measured value of the fluorine concentration of the solution containing no magnesium sulfate. This means that in the case where the calibration curve is made using a fluoride standard solution as usual, and the fluoride ion concentration is measured using a fluoride ion meter, the measurement value of the fluorine concentration of the solution containing 60,000 mg/L magnesium sulfate is approximately 1/10 of the actual . In contrast, according to the fluorine concentration measuring method of the present invention, since the matrix of the reference solution used to prepare the calibration curve is the same as the matrix of the sample water, it is possible to produce a calibration curve that takes into account the influence of coexisting ions, making it possible to accurately Measure the fluorine concentration of the sample water.

In addition, when preparing the reference solution, when the ion exchange reaction between fluoride ion and hydroxide ion occurs by contacting the sample water with the fluorine adsorbent, the pH value of the reference solution becomes much higher than the sample water However, it can be found that the influence of the difference in pH on the measured value of fluorine concentration is very small compared to the effect of coexisting ions. In particular, in the case of sample water containing a large amount of coexisting ions, the pH value tends to become smaller due to the buffering effect of the pH value of the coexisting ions. From the viewpoint of suppressing the influence of the difference in pH value as much as possible, the difference between the pH values of the sample water and the reference solution is preferably within 2.0, preferably within 1.5, and more preferably within 1.0.

The measurement of the potential value by the fluoride ion electrode meter is little affected by the temperature. From the point of view of eliminating the effect of potential measurement on temperature as much as possible, the temperature difference between the sample water and the reference solution during potential measurement is preferably within 30°C, preferably within 20°C, and within 10°C For better.

The fluorine concentration measuring method of the present invention exhibits particularly excellent effects when there are many coexisting ions other than fluoride ions in the sample water. Furthermore, in this case, the fluoride ion concentration can be measured more accurately. From such a viewpoint, in the present invention, it is preferable to use sample water having an ionic strength of 0.05 mol/L or more as the measurement object.

The fluorine concentration measurement method of the present invention has been described above. When the fluorine concentration measurement method of the present invention is applied to the measurement of the fluorine concentration in water to be treated (raw water) using a water treatment method using a fluorine adsorbent, It is also possible to use the treated water obtained by contacting the water to be treated with a fluorine adsorbent as the fluorine-removing sample water, and adding a fluorine compound to prepare a reference solution. In this case, the sample water (water to be treated) and the reference solution also have the same source, and both have substantially the same matrix. Therefore, the fluorine concentration of the sample water can be obtained by the fluorine concentration measurement method of the present invention.

Next, the fluorine concentration measurement device of the present invention will be described with reference to FIGS. 3 to 6. In addition, in the following description, parts overlapping with those described above will be omitted. By using the fluorine concentration measuring device of the present invention, the fluorine concentration measuring method of the present invention can be appropriately implemented. First, the fluorine concentration measuring device shown in FIG. 3 will be described.

The fluorine concentration measuring device includes a measurement unit 1 including a fluoride ion electrode meter 1, a first supply unit 4 that supplies sample water to the measurement unit 1, a fluorine removal unit 5 provided with a fluorine adsorbent, and a sample water supply to the fluorine removal unit 5 Second supply unit 6, a fluorine compound supply unit 7 that adds a fluorine compound to the defluorinated sample water discharged from the defluorinated unit 5 to obtain a reference solution, and a third supply that supplies the defluorinated sample water or the reference solution to the measuring unit 1 Unit 9. A calculation unit 10 that calculates the value or magnitude relationship of the fluorine concentration in the sample water based on the potential values of the sample water and the reference solution measured by the measurement unit 1.

The measurement unit 1 includes a fluoride ion electrode meter 2 and contains an analysis target liquid whose potential is measured by the fluoride ion electrode meter 2. For details of the fluoride ion electrode meter, please refer to the above description. The fluoride ion electrode meter 2 can communicate information with the calculation unit 10 in a wired or wireless manner. In FIG. 3, the measurement unit 1 is composed of a bath 3 containing an analysis target liquid, and a fluoride ion meter 2 provided in the bath 3, and the bath 3 has an analysis target liquid (discharge liquid 11) for measuring the potential The discharge part of the discharge. The measurement unit 1 may be composed of a pipeline of the analysis target liquid (specifically, sample water or a reference solution), and an electrode meter provided in this pipeline.

The fluorine removing unit 5 is provided with a fluorine adsorbent. For details of the fluorine adsorbent, please refer to the description above. In FIG. 3, the fluorine removing unit 5 is composed of an adsorption tower filled with a fluorine adsorbent. The fluorine removing section 5 may be an adsorption tank provided with a fluorine adsorbent or a pipeline provided with a fluorine adsorbent.

The first supply unit 4 supplies the sample water as the analysis target liquid to the measurement unit 1. The second supply unit 6 supplies the sample water to the defluorination unit 5. For details of the sample water, please refer to the description above. The first supply unit 4 and the second supply unit 6 are not particularly limited as long as they can supply the sample water to the measurement unit 1 or the defluorination unit 5. For example, a pipeline through which the sample water passes can be cited. The unit of the liquid feed pump in this pipeline, the container to transport the sample water, etc. In FIG. 3, the first supply unit 4 is shown as a pipeline communicating with the measuring unit 1. The second supply unit 6 is a pipeline communicating with the inlet side of the defluorination unit 5. These pipelines may also be provided with liquid inlets.料泵。 Material pump.

FIG. 3 shows the third supply unit 9 as a unit that supplies the defluorinated sample water discharged from the defluorinated unit 5 to the measuring unit 1. The third supply unit 9 is not particularly limited as long as it can supply the defluorinated sample water or the reference solution to the measurement unit 1, for example, a pipeline through which the defluorinated sample water or the reference solution passes is provided. The unit of the liquid feed pump in the pipeline, the container that transports the defluorinated sample water or the reference solution, etc. In FIG. 3, the third supply unit 9 is depicted as a pipeline communicating with the outlet side of the defluorination unit 5 and the measurement unit 1, and the defluorination sample water flows through this pipeline.

The fluorine compound supply unit 7 is a unit that supplies fluorine compounds to the defluorinated sample water. The reference solution is prepared by adding fluorine compounds to the defluorinated sample water. For details of fluorine compounds and reference solutions, please refer to the above description.

The fluorine compound supply unit 7 is not particularly limited as long as it can supply a solution or solid fluorine compound, for example, a pipeline through which a fluorine compound solution passes, a unit equipped with a liquid feed pump provided in this pipeline, a fluorine compound Feeders, containers for transporting fluorine compounds, etc. The fluorine compound is supplied from the fluorine compound supply unit 7 to, for example, a pipeline through which the defluorinated sample water passes, a bath for temporarily storing the defluorinated sample water, a bath 3 of the measuring section 1, and the like. In FIG. 3, the fluorine compound solution is stored in the storage tank 8, and the fluorine compound solution is supplied from the storage tank 8 to the bath 3 of the measuring section 1 by the fluorine compound supply unit 7. The fluorine compound solution supplied to the bath 3 by the fluorine compound supply unit 7 is mixed with the defluorinated sample water in the bath 3. As the fluorine compound solution, it is convenient to use a fluorine standard solution of known fluorine concentration. In this case, the fluorine compound supply unit 7 is a fluorine standard solution supply unit.

In the fluorine concentration measuring apparatus shown in FIG. 3, first, the sample water is supplied to the bath 3 of the measuring section 1 by the first supply unit 4, and the potential of the sample water is measured by the fluoride ion meter 2 to obtain the potential value P. The obtained potential value P is temporarily stored in the calculation unit 10. When the potential measurement of the sample water is completed, the sample water is discharged from the bath 3. On the other hand, the second supply unit 6 supplies the sample water to the defluorination unit 5 and removes the fluoride ions in the sample water. The defluorinated sample water discharged from the defluorinated part 5 is transferred to the bath 3 of the measuring part 1 by the third supply unit 9. The fluorine compound is added to the fluorine-removed sample water stored in the bath 3 by the fluorine compound supply unit 7, and a (first) reference solution having a fluorine concentration C1 is prepared in the bath 3. The potential of this (first) reference solution is measured by the fluoride ion electrode meter 2 to obtain the potential value P1. The obtained potential value P1 is stored in the calculation unit 10. At this time, the set value of the (first) reference solution's fluorine concentration C1 may be input to the calculation unit 10, and the calculation unit 10 controls the fluorine compound supply unit 7 to supply the set amount through the fluorine compound supply unit 7 Of fluorine compounds. By comparing the potential value P of the sample water thus obtained with the potential value P1 of the (first) reference solution using the calculation unit 10, it can be determined that the fluorine concentration of the sample water is relative to the fluorine concentration C1 of the (first) reference solution Size relationship.

In addition, in the above description, after the potential measurement of the sample water is performed by the fluoride ion meter 2 to obtain the potential value P, the sample water is discharged from the bath 3, however, the sample water discharged from the bath 3 may also be supplied to Fluoride removal section 5. In this case, for example, the second supply unit 6 is provided as a pipeline communicating with the outlet side of the measurement section 1 (the discharge section of the bath 3) and the inlet side of the defluorination section 5, this pipeline may also be provided with a liquid Feed pump.

In the fluorine concentration measuring apparatus shown in FIG. 3, after the potential measurement of the first reference solution, the fluorine compound may be further added to the first reference solution by the fluorine compound supply unit 7 to prepare a second reference solution. Alternatively, before the potential measurement of the first reference solution, the second reference solution may be prepared without adding the fluorine compound to the first reference solution. In this case, the potential of the second reference solution is measured by the fluoride ion meter 2 to obtain the potential value P2. The obtained potential value P2 is stored in the calculation unit 10. At this time, the set value of the fluorine concentration C2 of the second reference solution may be input to the calculation unit 10, and the calculation unit 10 controls the fluorine compound supply unit 7 so that the fluorine compound supply unit 7 supplies the set amount of fluorine Compound. Based on the potential value P1 of the first reference solution and the potential value P2 of the second reference solution, the calculation unit 10 creates a calibration curve indicating the relationship between the fluorine concentration and the potential value, thereby calculating the corresponding sample water The value of the fluorine concentration of the potential value P.

4 to 6, another example of the structure of the fluorine concentration measuring device of the present invention will be described. In addition, in the description of FIGS. 4 to 6, the description of the parts that overlap with FIG. 3 will be omitted.

The fluorine concentration measuring device shown in FIG. 4 has a water intake section 12 for receiving sample water, and is provided with a first supply line communicating with the inlet side of the water intake section 12 and the measurement section 1 as the first supply unit 4, and As the second supply unit 6, a second supply line communicating with the inlet side of the water intake unit 12 and the fluorine removal unit 5 is provided. The first supply line and/or the second supply line may be provided with a liquid feed pump. By setting the water taking part 12 in this way, the reference solution to be subjected to potential measurement in the reference solution measurement step can be the same source as the sample water to be subjected to potential measurement in the sample water measurement step.

The fluorine concentration measuring device shown in FIG. 4 is further provided with a mixing section 13 which mixes the fluorine removal sample water discharged from the fluorine removal section 5 and the fluorine compound supplied from the fluorine compound supply unit 7 with each other. In FIG. 4, the mixing unit 13 is provided in a pipeline communicating with the outlet side of the fluorine removing unit 5, and it is preferably installed in an inline mixer or the like, for example. In the mixing section 13, the fluorine-removing sample water and the fluorine compound are mixed to prepare a reference solution. In FIG. 4, the third supply unit 9 is provided as a pipeline communicating with the mixing section 13 and the measuring section 1, and supplies the reference solution to the measuring section 1. In addition, although not shown in the figure, the mixing section 13 may be provided as a mixing tank.

The fluorine concentration measuring device shown in FIG. 5 is provided with a first measuring section 1A for analyzing sample water and a second measuring section 1B for analyzing a reference solution as a measuring section. In FIG. 5, the first measuring section 1A is composed of a bath 3A containing sample water, and a fluoride ion meter 2A provided in the bath 3A, and the second measuring section 1B is composed of a bath 3B containing a reference solution, and a The fluoride ion electrode meter 2B in the bath 3B is composed. The bath 3A and the bath 3B are provided with a discharge unit for discharging the analysis target liquid (discharge liquids 11A, 11B) after measuring the potential. In this case, the first supply unit 4 supplies the sample water to the first measurement unit 1A, and the third supply unit 9 supplies the defluorinated sample water or the reference solution to the second measurement unit 1B. Furthermore, the measurement unit 10 calculates the value or magnitude relationship of the fluorine concentration in the sample water based on the potential value of the sample water measured by the first measurement unit 1A and the potential value of the reference solution measured by the second measurement unit 1B . As described above, if the first measurement unit 1A for analyzing the sample water and the second measurement unit 1B for analyzing the reference solution are provided, the value or the size relationship of the fluorine concentration in the sample water can be calculated more quickly.

The fluorine concentration measuring device shown in FIG. 6 is set to use a fluorine compound solution as the fluorine compound added to the reference solution, and at the same time, add a solution in which the fluorine compound solution is in contact with the fluorine adsorbent to the sample water. The fluorine concentration measuring device shown in FIG. 6 includes a second fluorine removing unit 14 provided with a fluorine adsorbent and supplying a fluorine standard solution, and supplying the fluorine removing standard solution discharged from the second fluorine removing unit 14 to the measuring unit 1的第 fourth supply unit 15 For details of the second defluorination unit 14, please refer to the description of the above defluorination unit 5. The fourth supply unit 15 is not particularly limited as long as it can supply the solution discharged from the second defluorinating unit 14 to the measuring unit 1. For example, a pipeline through which the solution passes and a device provided in the pipeline The liquid feed pump unit, the container that transports this solution, etc. In FIG. 6, the fourth supply unit 15 is illustrated as a pipeline that communicates with the outlet side of the second defluorinating unit 14 and the measuring unit 1, and this pipeline may be provided with a liquid feed pump. The pipeline of the fourth supply unit 15 may be connected to the pipeline of the first supply unit 4 for supplying the sample water to the measurement unit 1 and communicate with the measurement unit 1 via this pipeline. In the fluorine concentration measuring apparatus shown in FIG. 6, it is convenient to use a fluorine standard solution as the fluorine compound solution. In this case, the fourth supply unit 15 supplies the fluorine removal standard solution discharged from the second fluorine removal unit 14 To measurement section 1.

The various embodiments of the fluorine concentration measuring apparatus of the present invention have been described above with reference to FIGS. 3 to 6. However, the structural elements of the embodiments shown in FIGS. 3 to 6 may be arbitrarily combined. For example, the water taking part 12 and the mixing part 13 shown in FIG. 4 can also be provided in other implementations, and the structure of providing the complex measurement part 1 shown in FIG. 5 can also be applied to other implementations, and In other embodiments, the second defluorination unit 14 shown in FIG. 6 can also be provided.

The fluorine concentration measurement method of the present invention can be performed in combination with various water treatment methods. Therefore, the present invention also provides a water treatment method combining the above fluorine concentration measurement method.

The water treatment method of the present invention is, for example, a water treatment method that removes at least a part of fluoride ions from water containing fluoride ions to obtain treated water, and can use the fluorine concentration measurement method described above to treat the treated water as For sample water, measure the fluorine concentration in the treated water. The treated water may be, for example, treated water of the entire plant, or may be treated water that is subjected to a defluorination unit operation. By measuring the fluorine concentration in the treated water by the fluorine concentration measuring method of the present invention, the fluorine concentration in the treated water can be measured simply and accurately. In this way, it is possible to judge whether the water treatment is properly performed and whether the treated water quality is appropriate.

The water containing fluoride ions is not particularly limited as long as it contains fluoride ions in any form (for example, free form, salt form, complex form), and examples include waste water generated by the power plant; iron, steel, and non-ferrous metals. , Machinery, metal processing, electroplating, coating, electronic parts, glass, cement, etc. Wastewater generated by various factories; landfill leachate; organic waste water such as sewage, human waste liquid, livestock manure, etc.; process wastewater of various factories, etc. Furthermore, it may be water in a natural environment such as river water, lake water, ground water, sea water, and the like.

In the treatment for removing at least a part of fluoride ions from water containing fluoride ions, the removal of fluorine ions may be the primary purpose, or the removal of fluoride ions may be a secondary purpose. As the treatment method for removing fluorine as the main purpose, for example, a treatment method of solid-liquid separation by adding calcification of slaked lime or calcium chloride, and addition of aluminide such as aluminum sulfate or aluminum chloride Treatment method for solid-liquid separation, treatment method for solid-liquid separation by adding magnesium sulfate or magnesium hydroxide and the like, use of alumina-based adsorbents, ferrite-based adsorbents, zirconium-based adsorbents , Cerium-based adsorbents and other methods of adsorption and removal.

The water treatment method of the present invention is also a water treatment method in which at least a part of fluoride ions are removed from water containing fluoride ions to obtain treated water. The fluorine concentration measurement method described above can also be used to measure the Fluorine concentration. By measuring the fluorine concentration in the fluoride ion-containing water using the fluorine concentration measurement method of the present invention, it becomes possible to perform water treatment under appropriate conditions. For example, when chemicals such as calcification, aluminide, or magnesium compound described above are added to water containing fluoride ions to remove at least a part of the fluoride ions, the water containing fluoride ions is used as the sample water by The measurement result of the fluorine concentration of the water containing fluoride ions determines the amount of chemicals added, by which an appropriate amount of chemicals can be added, and the fluorine removal treatment can be performed efficiently. Alternatively, when water containing fluoride ions is introduced into a fluorine adsorption tower filled with a fluorine adsorbent to remove at least a part of fluoride ions, the water containing fluoride ions may be used as the sample water based on the water containing fluoride ions. Fluorine concentration measurement results dilute water containing fluoride ions. In this case, by determining the dilution rate based on the measurement result of the fluorine concentration of the water containing fluorine ions, it is possible to appropriately perform the fluorine removal treatment in the fluorine adsorption tower and appropriately suppress the passage of the discharge from the fluorine adsorption tower Fluorine concentration of treated water.

The water treatment method of the present invention may also be a water treatment method that uses the fluorine concentration measurement method of the present invention to measure both the water to be treated and the treated water. In this case, by measuring the fluorine concentration of the water to be treated and the treated water using the fluorine concentration measurement method of the present invention, it becomes possible to perform water treatment under appropriate conditions, and it is also possible to verify the conditions Whether it can be handled properly. The water treatment method of the present invention may also be a water treatment method that uses the fluorine concentration measurement method of the present invention to measure intermediately-treated water from the water to be treated to obtain the treated water.

The present invention further provides a water treatment device, which is a water treatment device that removes at least a part of fluoride ions from water containing fluoride ions to obtain treated water, and includes the fluorine concentration measurement device of the present invention. The water treatment device of the present invention is preferably a water treatment device capable of performing the water treatment method described above, for example, a water treatment device including a fluorine removal tank that can contain water containing fluoride ions and is provided with a chemical addition unit Better. Examples of the added chemicals include the above-described calcifications, aluminides, and magnesium compounds. As the chemical addition unit, a chemical liquid pump, a feeder, etc. may be mentioned. The water treatment device of the present invention may also be a water treatment device having a fluorine adsorption bath or a fluorine adsorption tower provided with a fluorine adsorbent. As the fluorine adsorbent, an alumina-based adsorbent, a ferrite iron-based adsorbent, Zirconium adsorbent, cerium adsorbent, etc.

The water treatment device of the present invention may be a water treatment device that collects water containing fluoride ions as sample water, or a water treatment device that collects treated water as sample water, or it may also collect water of both Processing device. Furthermore, the water in the middle of the process from the water to be treated to the processed water can be collected as the sample water.

FIG. 7 illustrates an example of the water treatment device of the present invention. The water treatment device shown in FIG. 7 is an example of a device in which a plurality of fluorine adsorption towers are connected in series. The first adsorption tower 21 and the second adsorption tower 22 are provided, and a series connection pipe 24 connecting the outlet side of the first adsorption tower 21 and the inlet side of the second adsorption tower 22 is provided. In this way, the first adsorption tower 21 It is connected in series with the second adsorption tower 22 as a fluorine adsorption tower. The fluoride ion-containing water (water to be treated) 31 passes through the pipeline 23 provided as the water to be treated communicated with the inlet side of the first adsorption tower 21, and is first introduced into the first adsorption tower 21, and then from the first adsorption tower 21 The intermediate treated water 32 of the effluent water is connected to the second adsorption tower 22 through the pipeline 24 connected in series and passed through the pipeline 25 of the treated water connected to the outlet side of the second adsorption tower 22 to obtain Processed water 33.

In the water treatment device shown in FIG. 7, at least one of water 31 containing fluoride ions, intermediate-processed water 32, and treated water 33 can be used as the sample water introduced into the fluorine concentration measurement device. For example, by measuring the fluorine concentration of the fluoride ion-containing water 31, the fluorine concentration of the fluoride ion-containing water 31 can be adjusted to a concentration that can be appropriately processed by the first adsorption tower 21 and the second adsorption tower 22. That is, when the fluorine concentration of the water 31 containing fluoride ions is too high, the fluorine concentration of the water 31 containing fluoride ions can be adjusted by dilution with water. By measuring the fluorine concentration of the intermediate-processed water 32, it is possible to appropriately determine the time point at which the fluorine adsorbent provided in the first adsorption tower 21 is replaced or regenerated. By measuring the fluorine concentration of the treated water 33, it can be confirmed whether the first adsorption tower 21 and the second adsorption tower 22 are properly subjected to the fluorine adsorption treatment, and it is possible to appropriately determine the The time point when the fluorine adsorbent is replaced or regenerated.

When measuring the fluorine concentration of water 31 containing fluoride ions, intermediate water 32, and treated water 33, a reference solution can be prepared for the measurement of each sample water, however, the nature of the water 31 containing fluoride ions changes little In this case, the fluoride ion-containing water 31, the intermediate-treated water 32, and the treated water 33 may also share the reference solution. Furthermore, in the case where the fluorine concentration of the treated water 33 is very low, the treated water 33 may be used as a reference solution, and the water 31 containing fluoride ions and the intermediate-treated water 32 may be used as sample water.

The invention can be applied to measure the fluoride ion concentration in various waste water and water in natural environment.

This application is based on Japanese Patent Application No. 2018-079024 filed on May 21, 2018, and claims its priority. The entire contents of the specification of Japanese Patent Application No. 2018-079024 filed on May 21, 2018 are incorporated by reference in this specification.

1. 1A, 1B‧‧‧‧Measurement Department 2. 2A, 2B ‧‧‧ Fluoride electrode meter 3. 3A, 3B ‧‧‧ bath 4‧‧‧First supply unit 5‧‧‧Defluorination Department 6‧‧‧Second supply unit 7‧‧‧Fluorine compound supply unit 8‧‧‧Storage tank 9‧‧‧3rd supply unit 10‧‧‧Calculation Department 11, 11A, 11B 12‧‧‧Water Department 13‧‧‧ Mixed Department 14‧‧‧The second defluorination department 15‧‧‧ 4th supply unit 21‧‧‧The first adsorption tower 22‧‧‧The second adsorption tower 23‧‧‧ pipeline of water to be treated 24‧‧‧Pipe series connected 25‧‧‧ pipeline of treated water 31‧‧‧ water containing fluoride ion 32‧‧‧Intermediate water treatment 33‧‧‧ treated water

FIG. 1 is a flowchart showing the method for measuring the fluorine concentration of the present invention. 2 is a graph showing a calibration curve prepared according to the fluorine concentration measurement method of the present invention, and a graph obtained by plotting the potential value of the sample water of various fluorine concentrations and the measurement results of the fluorine concentration. FIG. 3 illustrates an example of the structure of the fluorine concentration measuring device of the present invention. FIG. 4 illustrates an example of the structure of the fluorine concentration measuring device of the present invention. FIG. 5 illustrates a structural example of the fluorine concentration measuring device of the present invention. FIG. 6 illustrates an example of the structure of the fluorine concentration measuring device of the present invention. FIG. 7 illustrates an example of the structure of the water treatment device of the present invention.

Claims (17)

A method for determining fluorine concentration includes the following steps: The step of measuring the potential of the sample water with a fluoride ion electrode meter to obtain the potential value P; The step of contacting the sample water with the fluorine adsorbent to obtain the sample water for removing fluorine; The step of adding a fluorine compound to the aforementioned fluorine-removing sample water to prepare a reference solution with a fluorine concentration of C1; The step of measuring the potential of the aforementioned reference solution with a fluoride ion meter to obtain the potential value P1; and The step of comparing the potential value P with the potential value P1 to determine the magnitude relationship between the fluorine concentration of the sample water and the fluorine concentration C1. A method for determining fluorine concentration includes the following steps: The step of measuring the potential of the sample water with a fluoride ion electrode meter to obtain the potential value P; The step of contacting the sample water with the fluorine adsorbent to obtain the sample water for removing fluorine; The step of adding a fluorine compound to the aforementioned fluorine-removing sample water to prepare the first reference solution with a fluorine concentration of C1; The step of preparing a second reference solution with a fluorine concentration of C2 by adding or not adding a fluorine compound to the aforementioned defluorinated sample water; The step of measuring the potential of the first reference solution with a fluoride ion electrode meter to obtain the potential value P1; The step of measuring the potential of the second reference solution with a fluoride ion meter to obtain the potential value P2; The steps of creating a calibration curve showing the correlation between the fluorine concentration and the potential value using the fluorine concentration C1, C2 and the potential values P1, P2; and The step of calculating the fluorine concentration of the sample water corresponding to the potential value P based on the calibration curve. The fluorine concentration measuring method as described in item 1 or 2 of the patent application scope, wherein in the step of formulating the aforementioned reference solution, a fluorine standard solution of known fluorine concentration is used as the fluorine compound added to the aforementioned fluorine-removing sample water. The fluorine concentration measurement method as described in item 3 of the patent application scope, wherein in the step of obtaining the potential value P, a fluorine removal standard solution obtained by contacting the fluorine standard solution with a fluorine adsorbent is added to the sample water and utilized The fluoride ion meter measures the potential of the resulting solution. The method for measuring the fluorine concentration as described in any one of the items 1 to 4 of the patent application range, wherein the ionic strength of the sample water is 0.05 mol/L to 3.5 mol/L. The method for measuring the fluorine concentration as described in any one of items 1 to 5 of the patent application range, wherein the sample water is flue gas desulfurization wastewater discharged from the flue gas desulfurization equipment. A fluorine concentration measuring device, including: Equipped with a measuring unit of fluoride ion meter; A first supply unit that supplies the sample water to the measurement section; Fluorine removal section equipped with fluorine adsorbent; A second supply unit that supplies the sample water to the fluorine removal unit; A fluorine compound supply unit for adding a fluorine compound to the fluorine removal sample water discharged from the fluorine removal part to obtain a reference solution; A third supply unit that supplies the defluorinated sample water or the reference solution to the measurement section; and A calculation unit that calculates the value or magnitude relationship of the fluorine concentration in the sample water based on the potential values of the sample water and the reference solution measured by the measurement unit. The fluorine concentration measuring device as described in item 7 of the patent application scope further includes a mixing section which mixes the fluorine removal sample water discharged from the fluorine removal section with the fluorine compound supplied from the fluorine compound supply unit to Prepare the reference solution. The fluorine concentration measuring device according to item 8 of the patent application range, wherein the mixing section is provided in a pipeline communicating with the outlet side of the fluorine removing section. The fluorine concentration measuring device according to any one of items 7 to 9 of the patent application scope, wherein a first measuring section for analyzing the sample water and a second measuring section for analyzing the reference solution are provided as the measuring section , The first supply unit supplies the sample water to the first measurement section, And the third supply unit supplies the defluorinated sample water or the reference solution to the second measurement unit. The fluorine concentration measuring device according to any one of items 7 to 10 of the patent application range, wherein the fluorine concentration measuring device further includes a water taking part that receives the sample water, and is provided with an inlet side of the water taking part and the measuring part The connected first supply line serves as the first supply unit, and a second supply line communicating with the inlet sides of the water intake section and the fluorine removal section is provided as the second supply unit. The fluorine concentration measuring device according to any one of items 7 to 11 of the patent application range, in which a fluorine standard solution of known fluorine concentration is used as the aforementioned fluorine compound. The fluorine concentration measuring device as described in item 12 of the patent application scope, wherein the fluorine concentration measuring device further includes: A second fluorine removing section provided with a fluorine adsorbent and supplying the aforementioned fluorine standard solution; and The fluoride removal standard solution discharged from the second fluorine removal section is supplied to the fourth supply unit of the measurement section. A water treatment method which removes at least a part of fluoride ions from water containing fluoride ions to obtain treated water, wherein the fluorine concentration as described in any one of patent application items 1 to 6 is used In the measurement method, the treated water is used as the aforementioned sample water, and the fluorine concentration in the treated water is measured. A water treatment method, which is a water treatment method in which chemicals are added from water containing fluoride ions to remove at least a part of fluoride ions, wherein the fluorine concentration measurement method as described in any one of the patent application items 1 to 6 is used Using fluoride ion-containing water as the sample water, the fluorine concentration in the fluoride ion-containing water is measured, and based on this measurement result, the amount of the chemical added to the fluoride ion-containing water is determined. A water treatment method which introduces water containing fluoride ions into a fluorine adsorption tower filled with a fluorine adsorbent to remove at least a part of the fluoride ions. The water treatment method uses any one of items 1 to 6 of the patent application In the method for measuring the fluorine concentration described in the item, the water containing fluorine ions is used as the sample water, the fluorine concentration in the water containing fluorine ions is measured, and based on the measurement result, the water containing fluorine ions is diluted. A water treatment device, which is a water treatment device that removes at least a part of fluoride ions from water containing fluoride ions to obtain treated water, wherein the aforementioned water treatment device includes, as described in any of items 7 to 13 of the patent application The fluorine concentration measuring device mentioned above.

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