JP2011215034A - Automatic fluorine analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic fluorine analyzer capable of analyzing fluorine concentration contained in a sample solution.SOLUTION: The automatic fluorine analyzer includes a weighing means of sampling and weighing a predetermined amount of a fluorine-containing solution; a distillation means of adding the weighed fluorine-containing solution and a mixture solution of sulfuric acid or perchloric acid, phosphoric acid and silicon dioxide powder dispersed therein to a distillation bath and performing steam distillation while supplying water vapor from a steam generator; a neutralization means of adding an acidic solution and/or a basic solution to the liquid that results from cooling the gas exhausted from the distillation bath and neutralizing it; and a fluorine concentration measurement means of adding a buffer solution to the neutralized liquid to measure a fluorine concentration by an ion electrode method. The analyzer includes a control device for performing the processing in the weighing, distillation, neutralization and fluorine concentration measurement means, in the order of weighing, distillation, neutralization and fluorine concentration measurement means.

Description

  The present invention relates to an automatic fluorine analyzer.

  Fluorine compounds are widely used in various applications such as the manufacture of electronic industrial products and functional pharmaceuticals. And in a manufacturing factory etc., the waste liquid containing a fluorine compound arises. Fluorine compounds are difficult to decompose and cause environmental degradation.

  There is a legal restriction on the discharge of fluorine-containing waste liquid, and according to the Water Pollution Control Law, the fluorine concentration in waste liquid discharged to public water areas other than sea areas is within 8 mg / L, and in waste liquid discharged to sea areas The fluorine concentration is determined to be within 15 mg / L. For this reason, when the fluorine-containing waste liquid is discharged, analysis of the amount of fluorine contained in the waste liquid is required.

  As a device capable of measuring the fluorine concentration in a solution containing fluorine, for example, there is a fluorine concentration measuring device in a zinc electrolyte (Patent Document 1), etc., but in the analysis of fluorine in various waste liquids, mainly JIS K0102. Analysis of the fluorine content based on the above has been conducted.

Japanese Patent Laid-Open No. 11-352099

  Until now, the analysis method based on JIS K0102 has been manually performed by an analyst for each sample. In the analysis method based on JIS K0102, there are problems such as preparation of reagents, management of distillation temperature, management of steam generation amount, pH adjustment, and the like, as well as requiring skill of the analyst.

  The present invention has been made in view of the above matters, and an object thereof is to provide an automatic fluorine analyzer that can easily measure the concentration of fluorine contained in a sample solution.

Fluorine automatic analyzer according to the present invention,
Measuring means for separating and weighing a predetermined amount of fluorine-containing solution;
A distillation means for performing steam distillation while adding the measured fluorine-containing solution and a mixed solution in which silicon dioxide powder is dispersed in sulfuric acid or perchloric acid and phosphoric acid, and supplying water vapor from a steam generator; ,
Neutralizing means for neutralizing the liquid obtained by cooling the gas discharged from the distillation tank by adding an acidic solution and / or a basic solution;
A fluorine concentration measuring means for adding a buffer solution to the neutralized liquid and measuring the fluorine concentration by an ion electrode method;
The measurement unit, the distillation unit, the neutralization unit, and the fluorine concentration measurement unit are processed, and the measurement unit, the distillation unit, the neutralization unit, and the fluorine concentration measurement unit are sequentially performed. A control device,
It is characterized by that.

Further, the steam generator is configured by arranging a heating device on a metal block in which a steam generation flow path is provided,
It is preferable that the control device supplies water quantitatively to the water vapor generation flow path so that the total amount of the supplied water is heated and evaporated to quantitatively supply water vapor to the distillation tank.

The distillation tank includes a distillation flask filled with the fluorine-containing solution, a metal container in which the distillation flask is accommodated, a heating device installed in the metal container, and the fluorine-containing solution in the distillation flask. And a temperature sensor for measuring the temperature of
It is preferable that the control device controls the heating device to maintain the temperature of the liquid in the distillation flask in a range of 140 ° C. or higher and 150 ° C. or lower.

  The automatic fluorine analyzer according to the present invention performs processing in the measuring means, distillation means, neutralizing means, and fluorine concentration measuring means, and in the order of measuring means, distillation means, neutralizing means, and fluorine concentration measuring means. And a control device to be performed. Therefore, the fluorine concentration in the sample solution containing fluorine can be easily measured without requiring the skill and labor of the analyst.

It is a schematic block diagram of the fluorine automatic analyzer which concerns on this invention. It is an external view of a distillation tank. It is sectional drawing of a distillation tank. (A) is a horizontal sectional view showing the structure of the steam generator, and (B) is a side perspective view showing the structure of the steam generator. (A) is a horizontal sectional view showing the structure of the measuring tank, (B) is an X-X 'sectional view of (A), and (C) is a Y-Y' sectional view of (A).

  The automatic fluorine analyzer according to the present embodiment includes a measuring unit, a distillation unit, a neutralizing unit, and a fluorine concentration measuring unit, and performs control in which the measuring unit, the distillation unit, the neutralizing unit, and the fluorine concentration measuring unit are sequentially performed. Equipment. Specifically, as shown in the schematic configuration diagram of FIG. 1, the fluorine automatic analyzer 1 mainly includes an autosampler 10, a metering tank 20, a distillation tank 30, a water vapor generator 40, and a neutralization tank 50. The measuring tank 60 and the control device 70 are provided.

  The autosampler 10 is a device in which a plurality of sample solutions containing fluorine are arranged, and the sample solutions are sequentially collected and supplied to the weighing tank 20.

  The measuring tank 20 is a tank in which the sample solution sorted by the autosampler 10 is filled and a predetermined amount of the sample solution is weighed.

  The distillation tank 30 is a tank that performs steam distillation of the sample solution using the steam generated by the steam generator 40.

  The neutralization tank 50 is a tank that is neutralized by adding an acidic solution or a basic solution to the solution in which the gas generated in the distillation tank 30 is cooled.

  The measurement tank 60 is a tank for measuring the fluorine concentration of the neutralized solution.

  The control device 70 is a device that controls processes performed in the auto sampler 10, the measurement tank 20, the distillation tank 30, the water vapor generation device 40, the neutralization tank 50, and the measurement tank 60, respectively.

  Hereinafter, the flow of measurement of the fluorine concentration in the sample solution by the fluorine automatic analyzer 1 will be described.

First, before driving the fluorine automatic analyzer 1, each sample solution is prepared as follows. A sample containing 30 μg or more of F ⁻ ions such as waste liquid is placed in a beaker or the like, a phenolphthalein solution (5 g / L) is added, and a sodium hydroxide solution (100 g / L) is added dropwise to make it slightly basic, followed by heating. To about 30 ml.

  Each sample solution thus prepared is set in the autosampler 10.

(Measuring means)
When the switch of the fluorine automatic analyzer 1 (not shown) is turned on, the sample solution set in the autosampler 10 is sent to the measuring tank 20 by a pump. A liquid level detection sensor 21 is installed in the measuring tank 20, and when the liquid level of the sample solution filled in the liquid level detection sensor 21 is detected, the supply of the sample solution from the autosampler 10 is stopped. As a result, a fixed amount (15 ml) of the sample solution is weighed.

(Distillation means)
Steam distillation is a method of distilling a high boiling point compound having a high vapor pressure at a temperature below the boiling point. Steam is continuously introduced into the distillation tank 30, the distillation tank 30 is brought into a heated state, the inside of the distillation tank 30 is filled with heated steam supplied from the steam generator 40, and the heated steam flowing out together with the fluorine compound is cooled by the cooling pipe 35. Cool and collect the target fluorine compound together with water.

The sample solution weighed as described above is sent from the weighing tank 20 to the distillation tank 30. A fixed amount (15 ml) of a mixed solution in which silicon dioxide (SiO ₂ ) powder is dispersed in perchloric acid and phosphoric acid filled in the reagent tank 22 is sent to the distillation tank 30. The mixed solution was prepared at a ratio of 1 g of silicon dioxide, 1 ml of phosphoric acid, and 40 ml of perchloric acid. In addition, silicon dioxide is added in order to cause the fluorine contained in the sample solution to react and produce tetrafluorosilicic acid (SiF ₄ ) in the distillation means described later. The silicon dioxide powder is blended with perchloric acid and phosphoric acid in the above blending, and the reagent tank 22 is stirred to uniformly disperse the silicon dioxide powder in the solution. It is sent to the distillation tank 30 together with perchloric acid and phosphoric acid. Note that sulfuric acid may be used in place of perchloric acid.

  As shown in FIGS. 2 and 3, the distillation tank 30 is installed so as to surround the outer periphery of the distillation flask 31 filled with the sample solution and the mixed solution, the metal container 32 in which the distillation flask 31 is accommodated, and the metal container 32. And a liquid thermometer 34 for measuring the temperature of the solution in the distillation flask 31. The band heater 33 is controlled by the control device 70 based on the difference between the target temperature in the distillation flask 31 and the current temperature, and allows the temperature in the distillation flask 31 to reach the target temperature in a short time and keep it at the target temperature. .

  When the distillation flask 31 is filled with the solution composed of the sample solution and the mixed solution, heating by the band heater 33 is started by the controller 70, and the solution in the distillation flask 31 is heated. First, the solution in the distillation flask 31 is heated until the temperature of the solution reaches 140 ° C.

When the thermometer 34 detects that the solution in the distillation flask 31 has reached approximately 140 ° C., the controller 70 supplies the steam from the steam generator 40 into the distillation flask 31. The fluorine compound in the solution reacts with silicon dioxide by heating to become gaseous silicon tetrafluoride (SiF ₄ ). Distillation from the distillation flask 31 is performed by the water vapor supplied with the silicon tetrafluoride.

  The control device 70 controls heating by the band heater 33 based on feedback from the liquid thermometer 34 so that the solution in the distillation flask 31 is maintained in a range of 140 ° C. or higher and 150 ° C. or lower. By controlling in this way, steam distillation of a fluorine compound is performed appropriately.

  Steam generated by steam distillation is sequentially discharged from the distillation tank 30, liquefied when passing through the cooling pipe 35, and flows into the neutralization tank 50. Before the steam distillation starts, the controller 70 adds 10 ml of pure water from the pure water tank 41 and 0.1 ml of an aqueous sodium hydroxide solution from the basic solution tank 52 to the neutralization tank 50. And during distillation, it controls so that the solution in the neutralization tank 50 may keep basicity. This is because the gas distilled from the distillation tank 30 is acidic, and the acidic gas that has not been liquefied is quickly absorbed into the solution. A pH meter 51 is installed in the neutralization tank 50. When the pH of the solution obtained by distillation is less than 8, the controller 70 appropriately adds an aqueous sodium hydroxide solution from the basic solution tank 52. The pH is controlled to be 8 or more.

  Steam distillation is performed until the liquid flowing into the neutralization tank 30 reaches a certain amount (90 ml). In addition, in the amount (15 ml) of the sample solution weighed in the present embodiment, when the liquid flowing into the neutralization tank 30 reaches 90 ml, the total amount of fluoride ions contained in the sample solution is distilled. Is recognized.

  Thus, since the solution in the distillation flask 31 is maintained in the range of 140 ° C. or higher and 150 ° C. or lower by the control device 70, the following problem does not occur. That is, when the temperature of the solution becomes low (when the temperature is lower than 140 ° C.), the supplied water vapor becomes water in the distillation flask 31 and the amount of the solution increases, and the vaporized gas is discharged by the water vapor. Decreases and vaporized fluorine does not distill from the distillation flask 31. On the other hand, when the temperature of the solution becomes high (when it is higher than 150 ° C.), perchloric acid is distilled off.

  Further, as shown in FIGS. 4A and 4B, the water vapor generating device 40 has a structure having a water vapor generating flow path 43, a rod-shaped heating device 44, and a temperature sensor 45 inside the metal block. . A metal having a large heat capacity, such as stainless steel, is used as the metal block. The metal block 42 is heated to about 150 ° C. by heating by the heating device 44. Based on the temperature detected by the temperature sensor 45, the control device 70 controls the heating device 44 so that the metal block 42 maintains about 150 ° C.

  And since the pure water supplied from the pure water tank 41 flows into the water vapor generation flow path 43 and the metal block 42 is heated as described above, the pure water that has flowed in is immediately heated to turn into water vapor, It is sent to the distillation tank 30. By controlling the amount of pure water supplied from the pure water tank 41 to the water vapor generation flow path 53 to 3 to 5 ml / min, all of the pure water that has flowed in is sent to the distillation tank 30 as water vapor. The distillation rate at 30 is also 3 to 5 ml / min. As described above, the vapor generation amount can be quantitatively grasped and supplied to the distillation tank 30, and 90 ml of distillate from which all the fluoride ions in the sample solution have flowed out can be obtained.

(Neutralizing means)
When the distillation is completed, the controller 70 neutralizes the obtained solution. The neutralization tank 50 is provided with a pH meter 51 and neutralized so that the pH of the distilled solution is in the range of 6.5 to 7.5. When the pH exceeds 6.5 to 7.5, the control device 70 controls the hydrochloric acid solution to be added from the acidic solution tank 53. On the other hand, when the pH is lower than 6.5 to 7.5, an aqueous sodium hydroxide solution is added from the basic solution tank 52.

  After neutralization as described above, the control device 70 adds pure water from the pure water tank 41 to the neutralization tank 50 to prepare a fixed amount (100 ml) of solution.

(Measurement of fluorine concentration)
The neutralized solution is then sent to the measuring tank 60. The neutralized solution is sent to the 50 ml measuring tank 60, and the remaining 50 ml is used for absorbance measurement.

  A buffer solution is added from the buffer solution tank 62 to the measurement tank 60. The buffer solution was dissolved by adding 58 g of sodium chloride and 1 g of diammonium hydrogen citrate to 500 ml of water, and adding 50 ml of acetic acid to this solution so that an aqueous sodium hydroxide solution (200 g / L) was adjusted to pH 5.2. After adjusting by dropping, a liquid prepared to 1 L by adding water is used. The controller 70 adds 5 ml of the buffer solution to the neutralized solution and adjusts the pH to 5.0 to 5.5.

  In the measurement tank 60, the potential is measured using the fluoride ion electrode 61 as an indicator electrode, and the fluoride ions in the solution are quantified.

  The measurement tank 61 has a structure in which a rod-shaped heating device 64 and a temperature sensor 65 are provided inside the metal container 63 as shown in FIGS. 5 (A), (B), and (C). In addition, a stirrer is provided in the metal container 63 so that the fluorine ion concentration of the solution becomes uniform. The control device 70 controls the heating by the heating device 64 based on the temperature detected by the temperature sensor 65, and maintains the metal container 63 at approximately 30 ° C. By using a metal having a relatively large heat capacity as the metal container 63, it is difficult to be affected by external temperature changes.

  In order to accurately determine fluoride ions in the solution by the ion electrode method, the temperature of the solution in the measurement tank 60 needs to be maintained at about 30 ° C. In the present embodiment, as described above, the metal container 63 having a large heat capacity is used, and the heating device 64 is controlled by the control device 70, whereby the solution in the measurement tank 60 can be kept at about 30 ° C. . This makes it possible to accurately determine the fluorine ion concentration even in the ion electrode method.

  As described above, the automatic fluorine analyzer 1 causes the control device 70 to perform processing in the measuring means, the distillation means, the neutralizing means, and the fluorine concentration measuring means, and the measuring means, the distillation means, the neutralizing means, and the fluorine. Since the measurement is automatically performed in the order of the concentration measuring means, the fluorine concentration in the sample solution containing fluorine can be easily measured without requiring the skill and labor of the analyst.

  In the above, an example in which the distillation tank 30 and the neutralization tank 50 are one set has been described, but a plurality of sets of the distillation tank 30 and the neutralization tank 50 may be provided. By providing a plurality of sets of the distillation tank 30 and the neutralization tank 50, a large number of sample solutions can be efficiently analyzed in a short time.

DESCRIPTION OF SYMBOLS 1 Fluorine automatic analyzer 10 Autosampler 20 Measuring tank 21 Liquid level detection sensor 22 Reagent tank 30 Distillation tank 31 Distillation flask 32 Metal container 33 Band heater 35 Cooling pipe 34 Thermometer 40 Steam generator 41 Pure water tank 42 Metal block 43 Steam Generation channel 44 Heating device 45 Temperature sensor 50 Neutralization tank 51 pH meter 52 Basic solution tank 53 Acidic solution tank 60 Measurement tank 61 Fluoride ion electrode 62 Buffer solution tank 63 Metal container 64 Heating device 65 Temperature sensor 70 Control device

Claims (3)

Measuring means for separating and weighing a predetermined amount of fluorine-containing solution;
A distillation means for performing steam distillation while adding the measured fluorine-containing solution and a mixed solution in which silicon dioxide powder is dispersed in sulfuric acid or perchloric acid and phosphoric acid, and supplying water vapor from a steam generator; ,
Neutralizing means for neutralizing the liquid obtained by cooling the gas discharged from the distillation tank by adding an acidic solution and / or a basic solution;
A fluorine concentration measuring means for adding a buffer solution to the neutralized liquid and measuring the fluorine concentration by an ion electrode method;
The measurement unit, the distillation unit, the neutralization unit, and the fluorine concentration measurement unit are processed, and the measurement unit, the distillation unit, the neutralization unit, and the fluorine concentration measurement unit are sequentially performed. A control device,
Fluorine automatic analyzer characterized by that. The steam generator is configured by arranging a heating device on a metal block in which a steam generation flow path is provided,
2. The control device according to claim 1, wherein the control device supplies water quantitatively to the water vapor generation flow path, thereby heating and evaporating the entire amount of supplied water and supplying water vapor quantitatively to the distillation tank. The fluorine automatic analyzer described. The distillation tank includes a distillation flask filled with the fluorine-containing solution, a metal container in which the distillation flask is accommodated, a heating device installed in the metal container, and a temperature of the fluorine-containing solution in the distillation flask. A temperature sensor for measuring, and
3. The fluorine automatic analyzer according to claim 1, wherein the control device controls the heating device to maintain the temperature of the liquid in the distillation flask in a range of 140 ° C. or more and 150 ° C. or less.

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