JP2008076253A - Selenium analyzer and selenium fractional determination method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a selenium analyzer capable of rapid and accurate measurement of the respective concentrations of tetravalent selenium and hexavalent selenium in wastewater, and to provide a selenium fractional determination method. <P>SOLUTION: The selenium analyzer 10 has a selenium separation part 12 for fractionating a part of a sample, collected from waste water containing tetravalent selenium and hexavalent selenium into tetravalent selenium and hexavalent selenium; a selenium reducing part 19 for supplying a part of another sample to a solution, which contains an organic reducing agent 14; an acid 16 and a photocatalyst 17 to be irradiated with ultraviolet rays 18 for reducing hexavalent selenium and tetravalent selenium to metal selenium and hydrogen selenide; a selenium hydrogenating part 24 for reducing tetravalent selenium or metal selenium to hydrogen selenide by an acid 21 and a reducing agent 23; and a selenium analyzing part 25 for analyzing hydrogen selenide, that is reduced in the selenium hydrogenating part 24 for measuring the concentration of tetravalent selenium and the concentration of total selenium. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a selenium analyzer capable of measuring concentrations of tetravalent and hexavalent selenium in a solution in which tetravalent and hexavalent selenium are dissolved, and a method for fractional determination of selenium.

  In water quality standards such as tap water such as tap water and various effluents, the concentration of selenium (Se) is defined, and the selenium (Se) drainage standard is defined as 0.1 mg / l. Therefore, there are various treatment methods such as a catalytic reduction method, a microbial reduction method, and a chemical injection treatment method as a treatment method for waste water containing such selenium (Se).

  In addition, for example, coal and heavy oil burned at smelters and thermal power plants have a high concentration of selenium (Se), and part of the gasified selenium (Se) is absorbed by the desulfurization absorbent. As a result, the wastewater containing selenium (Se) does not satisfy the standard value, so that wastewater treatment is required.

Selenium has tetravalent and hexavalent forms, and tetravalent selenium (Se ⁴⁺ ) can be coprecipitated with a hydroxide such as iron and can be treated relatively easily. Valent selenium (Se ⁶⁺ ) is a difficult to process form. Further, tetravalent selenium (Se ⁴⁺ ) and hexavalent selenium (Se ⁶⁺ ) often have different optimum processing conditions. In order to establish an appropriate treatment method, tetravalent selenium (Se ⁴⁺⁾ in a solution is used. ) And hexavalent selenium (Se ⁶⁺ ).

  As a method for separately quantifying selenium (Se) for each form, the selenium compound in the sample solution is separated into each compound or existing form by passing it through an ion exchange separation column of an ion exchange chromatography apparatus together with an eluent. There is a method for quantifying the content (Patent Document 1).

Further, the concentration of tetravalent selenium in a solution in which tetravalent selenium (Se ⁴⁺ ) and hexavalent selenium (Se ⁶⁺ ) are dissolved is measured. Separately, tetravalent selenium (Se ⁴⁺ ) and hexavalent selenium (Se ⁶⁺ ) are measured. ) is reduced to 6-valent selenium (Se ⁶⁺⁾ a tetravalent selenium solution of (Se ^4+), the total is the total amount of tetravalent selenium (Se ⁴⁺⁾ and hexavalent selenium (Se ⁶⁺⁾ There is a method of measuring the selenium concentration and calculating the respective concentrations of tetravalent selenium (Se ⁴⁺ ) and hexavalent selenium (Se ⁶⁺ ) from the obtained tetravalent selenium concentration and total selenium concentration (Patent Document 2). .

JP-A-11-2623 Japanese Patent Laid-Open No. 11-142387

However, tetravalent selenium when measuring the total selenium concentration of the total amount of (Se ⁴⁺⁾ and hexavalent selenium (Se ^6+), tetravalent selenium (Se ⁴⁺⁾ and hexavalent selenium (Se ⁶⁺⁾ If the reduction is not sufficiently performed, the total selenium concentration in the wastewater may not be accurately measured. Therefore, there is a problem that the tetravalent selenium concentration and the hexavalent selenium concentration in the waste water cannot be accurately quantified. As a result, there is a problem that the amount of chemicals required for wastewater treatment cannot be supplied to the wastewater, and cannot always be satisfied below the selenium wastewater standard of 0.1 mg / l or less.

In view of the above problems, the present invention provides a selenium analyzer capable of measuring the concentrations of tetravalent selenium (Se ⁴⁺ ) and hexavalent selenium (Se ⁶⁺ ) in waste water quickly and accurately, and fractional determination of selenium. The challenge is to provide a law.

  The first invention of the present invention for solving the above-mentioned problem is to extract a part of waste water containing tetravalent and hexavalent selenium and to separate the tetravalent selenium and the hexavalent selenium contained in the waste water. The selenium separation unit, the other part of the waste water is extracted, an organic reducing agent supplied from the organic reducing agent supply unit, an acid supplied from the first acid supply unit, and a solution containing a photocatalyst. Supplied from a second acid supply unit, and a selenium reduction unit that reduces the hexavalent selenium and tetravalent selenium contained in the waste water to metal selenium or hydrogen selenide by irradiating with ultraviolet light. A selenium hydrogenation unit that reduces the tetravalent selenium or the metal selenium supplied from the selenium separation unit and the selenium reduction unit to hydrogen selenide by an acid and a reducing agent supplied from a reducing agent supply unit; Reduction in the selenium hydrogenation part The selenium analysis unit that analyzes the hydrogen selenide and measures the concentration of the tetravalent selenium contained in the wastewater and the concentration of the total selenium of the tetravalent selenium and the hexavalent selenium contained in the wastewater. The selenium analyzer is characterized by comprising:

  According to a second invention, in the selenium analyzer according to the first invention, the selenium separation unit is an ion exchange separation column for separating the tetravalent selenium and the hexavalent selenium in the waste water. is there.

  According to a third invention, in the selenium analyzer according to the first or second invention, the photocatalyst is any one of titanium dioxide, tungsten trioxide, platinum-supported titanium dioxide, or a combination thereof. is there.

  According to a fourth invention, in any one of the first to third inventions, the organic reducing agent is any one of formic acid, acetic acid, oxalic acid, citric acid, methanol, ethanol, glycol, phenol, or these. It is in the selenium analyzer characterized by being a combination.

  A fifth invention is the selenium analyzer according to any one of the first to fourth inventions, wherein the acid is any one of nitric acid and hydrochloric acid, or a combination thereof.

  A sixth invention is the selenium analyzer according to any one of the first to fifth inventions, wherein the ultraviolet light is light having a wavelength of 300 to 400 nm.

  A seventh invention is the selenium analyzer according to any one of the first to sixth inventions, wherein the reducing agent is sodium borohydride.

  According to an eighth invention, in any one of the first to seventh inventions, the selenium analyzing unit analyzes a selenium concentration with high sensitivity, a hydride generation-plasma emission spectrometer, or a hydride generation-atom. The selenium analyzer is an absorption spectrometer.

  According to a ninth invention, in any one of the first to eighth inventions, the concentration of the tetravalent selenium measured in the selenium analysis unit and the total selenium of the tetravalent selenium and the hexavalent selenium are measured. The selenium analyzer has a control device for determining the concentration of the hexavalent selenium from the concentration.

  In a tenth aspect of the present invention, wastewater containing tetravalent and hexavalent selenium is collected, and a part of the wastewater is separated from the tetravalent selenium and the hexavalent selenium contained in the wastewater using an ion exchange separation column. Then, the separated tetravalent selenium is supplied from an acid and a reducing agent to a solution and reduced to hydrogen selenide, and the concentration of the tetravalent selenium is measured, and another part of the waste water is used as a photocatalyst. Supplying to the solution which contains the organic reducing agent and the acid which it contains, it irradiates with ultraviolet light, reduces the hexavalent selenium and the tetravalent selenium contained in the waste water to metal selenium or hydrogen selenide, the tetravalent The selenium fractionation and quantification method is characterized by measuring the total selenium concentration of selenium and the hexavalent selenium and determining the hexavalent selenium concentration from the total selenium concentration and the tetravalent selenium concentration. .

  An eleventh invention is the selenium fractionation quantitative method according to the tenth invention, wherein the photocatalyst is any one of titanium dioxide, tungsten trioxide, platinum-supported titanium dioxide, or a combination thereof.

  In a twelfth aspect based on the tenth or eleventh aspect, the organic reducing agent is any one of formic acid, acetic acid, oxalic acid, citric acid, methanol, ethanol, glycol, phenol, or a combination thereof. Is a selenium fractional quantification method characterized by

  A thirteenth aspect of the invention is the selenium fractionation quantitative method according to any one of the tenth to twelfth aspects of the invention, wherein the acid is any one of nitric acid and hydrochloric acid, or a combination thereof.

  A fourteenth invention is the selenium fractionation quantification method according to any one of the tenth to thirteenth inventions, wherein the ultraviolet light is light having a wavelength of 300 to 400 nm.

  A fifteenth aspect of the invention is the selenium fractionation quantification method according to any one of the tenth to fourteenth aspects of the invention, wherein the reducing agent is sodium borohydride.

  A sixteenth invention is characterized in that, in any one of the tenth to fifteenth inventions, the selenium concentration is analyzed using a hydride generation-plasma emission spectrometer or a hydride generation-atomic absorption spectrometer. It is in the selenium fractionation quantitative method.

According to the present invention, in the selenium reducing unit, by supplying a part of the sample extracted from the waste water to a solution containing an organic reducing agent, an acid, and a photocatalyst and irradiating with ultraviolet light (UV), Since the tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ) contained in the waste water can be rapidly reduced to metal selenium or hydrogen selenide (H ₂ Se), it is accurate and reliable. The tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ) can be quantified. Thereby, the drainage standard of selenium can always be maintained.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

A selenium analyzer according to this embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram illustrating a selenium analyzer according to the present embodiment.
As shown in FIG. 1, the selenium analyzer 10 according to the present embodiment extracts a part of a sample collected from waste water 11 containing tetravalent selenium (Se ⁴⁺ ) and hexavalent selenium (Se ⁶⁺ ), and A selenium separation unit 12 for separating the tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ) contained in the waste water 11, and another part of the sample is extracted, and an organic reducing agent supply unit 13 is supplied to a solution containing the organic reducing agent 14 supplied from 13, the acid 16 supplied from the first acid supply unit 15, and the photocatalyst 17, and irradiated with ultraviolet light (UV) 18 to emit the waste water 11. A selenium reducing unit 19 for reducing the hexavalent selenium (Se ⁶⁺ ) and the tetravalent selenium (Se ⁴⁺ ) contained therein to metal selenium (Se ⁰ ) or hydrogen selenide (H ₂ Se); Acid 21 supplied from the second acid supply unit 20 and supply from the reducing agent supply unit 22 By a reducing agent 23, the selenium separation unit 12 and the said supplied from selenium reduction unit 19 tetravalent selenium (Se ⁴⁺⁾ or the metallic selenium (Se ⁰⁾ to hydrogen selenide (H ₂ Se) The selenium hydrogenation unit 24 to be reduced, and the hydrogen selenide (H ₂ Se) reduced in the selenium hydrogenation unit 24 are analyzed, and the concentration of the tetravalent selenium (Se ⁴⁺ ) contained in the waste water 11 And a selenium analysis unit 25 for measuring the total selenium concentration of the tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ) contained in the waste water 11.
In this embodiment, a system in which a sample collected from the waste water 11 is supplied to the selenium reduction unit 19 is a total selenium reduction processing system A, and a system supplied to the selenium separation unit 12 is a separation processing system B. To do.

In the present embodiment, in the all selenium treatment system A, a part of the waste water 11 supplied from the sample supply line L ₀ is supplied to the selenium reduction unit 19 through the separation processing line L _1, and the waste water 11 The total selenium of the hexavalent selenium (Se ⁶⁺ ) and the tetravalent selenium (Se ⁴⁺ ) contained in is reduced.

The selenium reducing unit 19 includes an organic reducing agent supply unit 13 that supplies the organic reducing agent 14, a first acid supply unit 15 that supplies the acid 16, and an organic reducing agent supplied from the organic reducing agent supply unit 13. 14 and a selenium reduction tank 26 containing a solution containing the acid 16 and titanium dioxide (TiO ₂ ) supplied from the first acid supply unit 15.

In this embodiment, formic acid (HCOOH) is used as the organic reducing agent 14. By adding this formic acid (HCOOH), the reduction effect of the hexavalent selenium (Se ⁶⁺ ) and the tetravalent selenium (Se ⁴⁺ ) contained in the waste water 11 can be promoted.

In this embodiment, hydrochloric acid (HCl) is used as the acid 16. By adding this hydrochloric acid (HCl), the reduction effect of the hexavalent selenium (Se ⁶⁺ ) and the tetravalent selenium (Se ⁴⁺ ) contained in the waste water 11 can be promoted.

The hexavalent selenium (Se ⁶⁺ ) and the tetravalent selenium (Se ⁴⁺ ) contained in the waste water 11 by irradiating the solution in the selenium reduction tank 26 with ultraviolet light (UV) 18. Reduced to metal selenium (Se ⁰ ) or hydrogen selenide (H ₂ Se).

That is, the hexavalent selenium (Se ⁶⁺ ) is reduced to the tetravalent selenium (Se ⁴⁺ ) as shown in the following formula (I).
SeO ₄ ²⁻ + 2H ⁺ + 2e ⁻ → SeO ₃ ²⁻ + H ₂ O (I)

The tetravalent selenium (Se ⁴⁺ ) is reduced to the metal selenium (Se ⁰ ) as shown in the following formula (II).
SeO ₃ ^2- + 6H ⁺ → Se ⁰ + 3H ₂ O (II)

Further, the metal selenium (Se ⁰ ) is reduced by hydrogenation to the hydrogen selenide (H ₂ Se) as in the following formulas (III) and (IV).
Se ⁰ + 2e ⁻ → Se ²⁻ (III)
Se ^2- + 2H ⁺ → H ₂ Se (IV)

In this way, the hexavalent selenium (Se) contained in the waste water 11 is irradiated by irradiating a solution containing formic acid (HCOOH), hydrochloric acid (HCl), and titanium oxide (TiO ₂ ) with ultraviolet light (UV). ⁶⁺ ) and the tetravalent selenium (Se ⁴⁺ ) can be reduced to metal selenium (Se ⁰ ) or hydrogen selenide (H ₂ Se) in a short time.

The hexavalent selenium (Se ⁶⁺ ) and the tetravalent selenium (Se ⁴⁺ ) contained in the waste water 11 are all reduced in a short time to be reduced to hydrogen selenide (H ₂ Se). Since the selenium concentration of the tetravalent selenium (Se ⁴⁺ ) and the selenium concentration of the hexavalent selenium (Se ⁶⁺ ) contained in the waste water 11 can be measured, the 4 contained in the waste water 11. The total selenium concentration of the selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ) can be accurately measured.

When the tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ) are reduced to metal selenium (Se ⁰ ) in the selenium reduction unit 19, the metal selenium (Se ⁰ ) The selenium hydrogenation section 24 is supplied via a selenium supply line L _2-1 .

When the tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ) are reduced to the hydrogen selenide (H ₂ Se) in the selenium reducing unit 19, the hydrogen selenide ( H ₂ Se) is directly supplied to the selenium analysis unit 25 via a selenium hydride supply line L _2-2 .

Here, the test results of reducing all selenium composed of the tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ) in the selenium reducing unit 19 will be described.

FIG. 2 is a configuration diagram showing the configuration of the apparatus used for the test.
As shown in FIG. 2, the test apparatus 30 includes a reaction tank 32 in which the sample solution 31 containing hexavalent selenium (Se ⁶⁺ ) is placed, and high-pressure mercury that irradiates the reaction tank 32 with ultraviolet light (UV). A lamp 33. Further, water (H ₂ O) 34 is circulated in the reaction layer 32 for cooling the sample solution 31 and supplied into the reaction layer 32 using nitrogen gas (N ₂ ) 35 as an inert gas. I tried to do it.
The reaction layer 32 is placed on a stirrer 36, and a stirrer 37 is placed in the reaction layer 32 and rotated so that the hexavalent selenium (Se ⁶⁺ ) in the sample solution 31 is converted into the sample solution 31. The sample solution 31 was stirred so as to be uniform.
Further, a copper sulfate solution (CuSO ₄ ) 38 was used as an absorbing solution for collecting the generated hydrogen selenide (H ₂ Se).
The reaction vessel 32, the high-pressure mercury lamp 33, and the copper sulfate solution (CuSO ₄ ) 38 were tested in a simple draft 39.
Further, “UM-102” (manufactured by USHIO) was used as the high-pressure mercury lamp 33 that generates ultraviolet light (UV), and the lighting of the high-pressure mercury lamp 33 was adjusted by a high-pressure mercury lamp power source 40.
Moreover, the wavelength of the irradiated ultraviolet light (UV) was set to 254 (nm), for example.

The selenium concentration (mg / l) of the tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ) in the sample solution 31 after 30 minutes, 60 minutes and 90 minutes from the start of the test Was measured. Also confirmed the color of the generated hydrogen selenide (H ₂ Se) The collected copper sulfate solution (CuSO ₄₎ 38 of the liquid.

The photocatalyst used in the test, the amount of the sample solution 31 (ml), the concentration of the hexavalent selenium (Se ⁶⁺ ) in the sample solution 31 (mg / l), the organic reducing agent used, and its Table 1 shows test conditions representing the concentration (nmol), the presence or absence of ultraviolet light (UV) irradiation, and the presence or absence of addition of hydrochloric acid (HCl).

Selenium concentrations (mg / l) of the tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ) in the sample solution 31 after 30 minutes, 60 minutes, and 90 minutes from the start of the test Table 1 shows the liquid color of the copper sulfate solution (CuSO ₄ ) 38 that collected the generated hydrogen selenide (H ₂ Se).
In addition, among the test examples, a relational diagram showing the relationship between the test start time (min) of Test Example 1 to Test Example 4 in Table 1 and the concentration (mg / l) of the hexavalent selenium (Se ⁶⁺ ). Is shown in FIG.

As shown in Table 1, the selenium concentration (mg / l) of hexavalent selenium (Se ⁶⁺ ), which was 10 (mg / l) at the start of the test, decreased after 30 minutes from the start of the test. Was confirmed. In particular, in Test Example 2 in which platinum-supported titanium dioxide (Pt—TiO ₂ ) was used as a photocatalyst, formic acid (HCOOH) was used as an organic reducing agent, and ultraviolet light (UV) was irradiated, the hexavalent selenium (Se ⁶⁺ ) was used. It was confirmed that the selenium concentration (mg / l) decreased to 5.1 (mg / l) after 30 minutes from the start of the test.

Further, it was confirmed that the selenium concentration (mg / l) of hexavalent selenium (Se ⁶⁺ ) decreased to 1.0 (mg / l) or less after 60 minutes from the start of the test. It was also confirmed that the selenium concentration (mg / l) of tetravalent selenium (Se ⁴⁺ ) decreased to 1.0 or less after 30 minutes from the start of the test.

Further, Test Example 4 in which platinum-supported titanium dioxide (Pt—TiO ₂ ) was used as a photocatalyst, formic acid (HCOOH) was used as an organic reducing agent, hydrochloric acid (HCl) was added to form an acidic solution, and ultraviolet light (UV) was irradiated. In Test Example 6 in which titanium dioxide (TiO ₂ ) was used as a photocatalyst, formic acid (HCOOH) was used as an organic reducing agent, hydrochloric acid (HCl) was added to form an acidic solution, and ultraviolet light (UV) was irradiated, After the lapse of minutes, it was confirmed that the selenium concentration (mg / l) of hexavalent selenium (Se ⁶⁺ ) had already decreased to 1.0 or less. It was also confirmed that the selenium concentration (mg / l) of tetravalent selenium (Se ⁴⁺ ) decreased to 1.0 or less after 30 minutes from the start of the test.

Therefore, from this test result, by using titanium dioxide (TiO ₂ ) or platinum-supported titanium dioxide (Pt—TiO ₂ ) as a photocatalyst and formic acid (HCOOH) as an organic reducing agent and irradiating with ultraviolet light (UV) It was confirmed that the hexavalent selenium (Se ⁶⁺ ) can be reduced in about 30 minutes from the start of the test.

Further, it was confirmed that the reduction reaction of the hexavalent selenium (Se ⁶⁺ ) was accelerated by further adding hydrochloric acid (HCl) to the solution containing the photocatalyst and the organic reducing agent to make an acidic solution.

Further, in this test, since the tetravalent selenium (Se ⁴⁺ ) was hardly confirmed, the hexavalent selenium (Se ⁶⁺ ) was reduced to the tetravalent selenium (Se ⁴⁺ ), and metal selenium (Se It is considered that the reduction reaction to ⁰ ) is instantaneous.

Further, in Test Example 7 and Test Example 8, a black precipitate of copper (I) selenide (Cu ₂ Se) is generated in the copper sulfate solution (CuSO ₄ ) 38 that collects the generated hydrogen selenide (H ₂ Se). It was confirmed that

Therefore, from this test result, since a black precipitate of copper (I) selenide (Cu ₂ Se) was produced in the copper sulfate solution (CuSO ₄ ), hydrogen selenide (H ₂ Se) was produced from metal selenium (Se ⁰ ). It was confirmed that the reduction reaction to) was also carried out.

In this example, a photocatalyst is used as a method for reducing the tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ). However, the present invention is not limited to this. For example, methods based on official methods based on hydrochloric acid addition-boiling reduction, microorganism-based reduction methods, catalytic reduction methods, ferrous ion reduction methods, hydrazine reduction methods, methods combining copper plate substitution, iron powder substitution and slaked lime neutralization A reduction treatment method by adding a reducing agent such as the above may be used.

In this embodiment, titanium dioxide (TiO ₂ ) or platinum-supported titanium dioxide (Pt—TiO ₂ ) is used as the photocatalyst 17. However, the present invention is not limited to this. Tungsten oxide (WO ₃ ) may be used, or any combination of titanium dioxide (TiO ₂ ), tungsten trioxide (WO ₃ ), and platinum-supported titanium dioxide (Pt—TiO ₂ ) may be used.

In this embodiment, formic acid (HCOOH) is used as the organic reducing agent 14, but the present invention is not limited to this. For example, acetic acid (CH ₃ COOH), oxalic acid (((( COOH) ₂ )), organic carboxylic acids such as citric acid (C ₆ H ₈ O ₇ ), methanol (CH ₃ OH), ethanol (C ₂ H ₅ OH), ethylene glycol ((CH ₂ OH) ₂ ), phenol Any one of hydroxyl organic carboxylic acids such as (C ₆ H ₅ OH) or a combination thereof may be used.

In this embodiment, hydrochloric acid (HCl) is used as the acid 16, but the present invention is not limited to this. For example, nitric acid (HNO ₃ ) or a combination thereof is used. Also good.

  In the present embodiment, the ultraviolet light (UV) 18 is preferably light having a wavelength of 300 to 400 nm in order to efficiently exhibit the effect of the photocatalyst.

Further, in this embodiment, in the separation processing system B, a part of the waste water 11 supplied from the sample supply line L ₀ is supplied to the selenium separation unit 12 through the separation processing line L _3, and the waste water 11 The tetravalent selenium (Se ⁴⁺ ) contained therein is reduced to quantify the tetravalent selenium (Se ⁴⁺ ).
The fractionation system B is provided with an ion exchange separation column 41 as the selenium separation unit 12.

The sample was supplied to an eluent 43 supplied from an elution tank 42 to the ion exchange separation column 41 of ion exchange chromatography packed with an ion exchange resin (preferably a strongly basic anion exchange resin). The eluent 43 is passed through. Thereby, since each selenium compound and the ion exchange resin have different affinities, the selenium compound in the sample solution can be separated. For example, the affinity of each selenide ion or selenium oxyacid ion to a strongly basic anion exchange resin is Se ²⁻ <SeO ₃ ²⁻ <SeO ₄ ²⁻ .

Thus, using the ion exchange separation column 41, SeO ₃ ^{2- as the} tetravalent selenium (Se ⁴⁺ ) and SeO ₄ ^{2- as the} hexavalent selenium (Se ⁶⁺ ) in the waste water 11 are obtained. By separating, it is possible to discharge the separated selenide ions of the hexavalent selenium (Se ⁶⁺ ) and extract only the selenide ions of the tetravalent selenium (Se ⁴⁺ ). Thereby, as described later, the tetravalent selenium (Se ⁴⁺ ) can be hydrogenated in the selenium hydrogenation unit 24 and the selenium analysis unit 25 can measure the selenium concentration.

The tetravalent selenium (Se ⁴⁺ ) separated in the ion exchange separation column 41 is supplied to the selenium hydrogenation section 24 through a tetravalent selenium supply line L ₄ .

  As the eluent 43, an alkaline solution such as a sodium hydroxide solution (NaOH) is used.

  The sample can be made acidic by adding an acid such as hydrochloric acid, nitric acid or sulfuric acid, if necessary, so that the selenium compound is ionized in the sample solution.

Further, in this embodiment, the tetravalent selenium (Se ⁴⁺ ) supplied from the selenium separator 12 through the tetravalent selenium supply line L ₄ , and the metal selenium supply line L ₂₋ from the selenium reducing unit 19 are used. _In order to hydrogenate the metal selenium (Se ⁰ ) supplied via ₁ , the second acid supply unit 20 that supplies the acid 21 and the reducing agent supply unit 22 that supplies the reducing agent 23 are included. A selenium hydrogenation unit 24 is provided. Further, an inert gas 45 is supplied from the inert gas supply unit 44 to the selenium hydrogenation unit 24. In this embodiment, argon (Ar) gas is used as the inert gas 45.

In the selenium hydrogenation unit 24, the tetravalent selenium (Se ⁴⁺ ) supplied from the selenium separation unit 12 via the tetravalent selenium supply line L ₄ is used as hydrochloric acid (HCl) supplied from the second acid supply unit 20. ) And sodium borohydride (NaBH ₄ ) supplied from the reducing agent supply unit 22 to reduce to hydrogen selenide (H ₂ Se).

Further, the metal selenium (Se ⁰ ) supplied from the selenium reduction unit 19 through the metal selenium supply line L _2-1 is supplied with hydrochloric acid (HCl) supplied from the second acid supply unit 20 and a reducing agent supply. Reduction to hydrogen selenide (H ₂ Se) is performed with sodium borohydride (NaBH ₄ ) supplied from the section 22.

In this embodiment, hydrochloric acid (HCl) is used as the acid 21 supplied from the second acid supply unit 20, but the present invention is not limited to this. For example, nitric acid (HNO ₃ ) or a combination of these may be used.

In this embodiment, sodium borohydride (NaBH ₄ ) is used as the reducing agent 23 supplied from the reducing agent supply unit 22, but the present invention is not limited to this, A reducing agent may be used.

In this embodiment, argon (Ar) gas is used as the inert gas 45. However, the present invention is not limited to this, and nitrogen (N ₂ ) gas may be used. .

In this example, the hydrogen selenide (H ₂ Se) reduced in the selenium hydrogenation unit 24 is analyzed, and the concentration of the tetravalent selenium (Se ⁴⁺ ) contained in the waste water 11 The selenium analysis unit 25 is provided for measuring the concentration of all selenium in the waste water, the tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ).

Thereby, since the concentration of selenium of hydrogen selenide (H ₂ Se) supplied from the selenium separation unit 12 and reduced in the selenium hydrogenation unit 24 can be analyzed, the tetravalent contained in the waste water can be analyzed. The concentration of selenium (Se ⁴⁺ ) can be measured.

The concentration of selenium of hydrogen selenide (H ₂ Se) supplied from the selenium reduction unit 19 and reduced in the selenium hydrogenation unit 24 and hydrogen selenide (H ₂ Se) supplied from the selenium reduction unit 19 Therefore, the total selenium concentration of the tetravalent selenium (Se ⁴⁺ ) and hexavalent selenium (Se ⁶⁺ ) contained in the waste water can be measured.

Further, the selenium analyzer 10 according to the present embodiment has a control device (CPU) 46 in the selenium analysis unit 25, and the concentration of tetravalent selenium (Se ⁴⁺ ) measured by the control device 46 and The concentration of the hexavalent selenium (Se ⁶⁺ ) is determined from the total selenium concentration of the tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ).

In this way, the measured values of the total selenium concentration of the tetravalent selenium (Se ⁴⁺ ) and hexavalent selenium (Se ⁶⁺ ) and the concentration value of the tetravalent selenium (Se ⁴⁺ ) are measured. By doing so, the concentration of hexavalent selenium (Se ⁶⁺ ) can be quantified.

  In the present embodiment, a hydride generation atomic absorption spectrometer or a hydride generation plasma emission spectrometer is used as the selenium analysis unit 25, but the present invention is not limited to this. For example, A plasma emission mass spectrometer, a liquid chromatography-plasma emission-mass spectrometer, or the like may be used.

In this example, hydrogen selenide (H ₂ Se) is obtained by the reaction of tetravalent selenium (Se ⁴⁺ ) with hydrochloric acid (HCl), sodium borohydride (NaBH ₄ ), and sodium hydroxide solution (NaOH). Is not affected by chlorine ions (Cl ⁻ ), sulfate ions (SO ₄ ²⁻ ), nitrate ions (NO ₃ ⁻ ) and hexavalent selenium (Se ⁶⁺ ), Even if these substances other than hydrogen selenide (H ₂ Se) are discharged as the drain 47, the selenium concentration of hydrogen selenide (H ₂ Se) can be analyzed accurately.

As described above, according to the present embodiment, since all of the hexavalent selenium (Se ⁶⁺ ) in the waste water can be quickly reduced, the tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se Since the total selenium concentration of Se ⁶⁺ ) can be accurately measured, the tetravalent selenium concentration and the hexavalent selenium concentration in the waste water can be accurately quantified.

  Thereby, the addition amount of chemicals required in the wastewater treatment can be supplied to the wastewater, and can always be satisfied to 0.1 mg / l or less which is the wastewater standard of the selenium.

  The selenium analyzer according to the present invention can be used not only for analysis of wastewater containing selenium, but also for analysis of wastewater containing harmful components such as other metals and heavy metals (such as mercury and arsenic).

Here, an exhaust gas treatment system for treating selenium in waste water using the selenium analyzer according to the embodiment of the present invention will be described with reference to FIG.
FIG. 4 is a conceptual diagram showing the configuration of the exhaust gas treatment system.
As shown in FIG. 4, the exhaust gas treatment system 50 using the selenium analyzer according to the present embodiment removes the dust in the exhaust gas 52 from the boiler 51 that generates steam for driving the steam turbine. An electric dust collector (EP) 53, a desulfurization device 54 for desulfurizing SOx in the exhaust gas 52 that has been dedusted to dilute sulfuric acid (H ₂ SO ₄ ), and a purified gas 55 desulfurized from the desulfurization device 54 A chimney 56 discharged to the outside and a selenium analyzer 10 for analyzing the selenium concentration in the waste water discharged from the desulfurizer 54 are provided. The selenium analyzer 10 is the same as the selenium analyzer 10 according to the first embodiment of the present invention, and the description thereof is omitted here.

  Here, in the boiler 51, for example, fuel such as coal and heavy oil is burned in a furnace in order to generate steam for driving a steam turbine (not shown) of the thermal power generation facility. The exhaust gas 52 of the boiler 51 contains sulfur oxide (SOx), and the exhaust gas 11 is denitrated by a denitration device (not shown), cooled by a gas heater, and then dedusted by an electric dust collector (EP) 53.

  Then, the desulfurization apparatus 54 performs desulfurization in the exhaust gas 52, and the desulfurized exhaust gas 52 becomes the purified gas 55 and is discharged from the chimney 56.

Further, the feed water used for desulfurization in the desulfurization apparatus 54 is discharged as drainage 57. The waste water 57 discharged from the desulfurization device 54 is obtained by collecting a part of the waste water 57 in the selenium analyzer 10 and the selenium concentration and tetravalence of tetravalent selenium (Se ⁴⁺ ) contained in the waste water 57. The selenium concentration of total selenium, which is the total amount of selenium (Se ⁴⁺ ) and hexavalent selenium (Se ⁶⁺ ), is analyzed, and tetravalent selenium (Se ⁴⁺ ) and hexavalent selenium (Se ⁴⁺ ) contained in the waste water 57 are analyzed. The selenium concentration of Se ⁶⁺ ) is quantified.

As a result of analyzing the selenium concentration of the tetravalent selenium (Se ⁴⁺ ) and the selenium concentration of all selenium, the selenium of tetravalent selenium (Se ⁴⁺ ) and hexavalent selenium (Se ⁶⁺ ) contained in the waste water 57 is analyzed. When the concentration value is equal to or higher than the reference value, the waste water treatment 58 is performed and then discharged.

When the selenium concentration values of tetravalent selenium (Se ⁴⁺ ) and hexavalent selenium (Se ⁶⁺ ) contained in the waste water 57 analyzed by the selenium analyzer 10 are below a reference value, The waste water 57 is discharged as it is.

Thus, according to the exhaust gas treatment system using the selenium analyzer according to this example, the hexavalent selenium (Se ⁶⁺ ) in the waste water is converted into metal selenium (Se ⁰ ) or hydrogen selenide (H ₂ Se). ) Quickly, all the selenium concentrations of the tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ) can be accurately measured. The selenium concentration and the hexavalent selenium concentration can be accurately quantified.

  Thereby, the addition amount of chemicals required in the wastewater treatment can be supplied to the wastewater, and can always be satisfied to 0.1 mg / l or less which is the wastewater standard of the selenium.

As described above, the selenium analyzer and the selenium fractional quantification method according to the present invention supply a part of the sample extracted from the waste water to a solution containing an organic reducing agent, an acid, and a photocatalyst, and emit ultraviolet light (UV ), The tetravalent selenium (Se ⁴⁺ ) and the hexavalent selenium (Se ⁶⁺ ) contained in the waste water are converted into metal selenium (Se ⁰ ) or hydrogen selenide (H ₂ Se). Since it can be rapidly reduced, it is suitable for accurately quantifying the concentration of tetravalent selenium and hexavalent selenium in waste water.

It is the schematic which shows the selenium analyzer which concerns on a present Example. It is a block diagram which shows the structure of the apparatus used for the test. FIG. 5 is a relationship diagram showing the relationship between the test start time (min) of Test Example 1 to Test Example 4 in Table 1 and the concentration (mg / l) of the hexavalent selenium (Se ⁶⁺ ). It is a conceptual diagram which shows the structure of an exhaust gas processing system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Selenium analyzer 11 Waste water 12 Selenium separation part 13 Organic reducing agent supply part 14 Organic reducing agent 15 First acid supply part 16 Acid 17 Photocatalyst 18 Ultraviolet light (UV)
19 Selenium reduction unit 20 Second acid supply unit 21 Acid 22 Reductant supply unit 23 Reductant 24 Selenium hydrogenation unit 25 Selenium analysis unit 26 Selenium reduction tank 30 Test apparatus 31 Sample solution 32 Reaction tank 33 High-pressure mercury lamp 34 Water ( H ₂ O)
35 Nitrogen gas (N ₂ )
36 Stirrer 37 Stirrer 38 Copper sulfate solution (CuSO ₄ )
39 Simplified draft 40 High pressure mercury lamp power source 41 Ion exchange separation column 42 Elution tank 43 Eluent 44 Inert gas supply 45 Inert gas A Total selenium reduction treatment system B Separation treatment system L ₀ Sample supply line L ₁ Separation treatment line L _2-1 metallic selenium supply lines L _2-2 selenide hydride feed line L ₃ fractionating line L ₄ 4-valent selenium supply line

Claims (16)

A selenium separation unit for extracting a part of the waste water containing tetravalent and hexavalent selenium, and separating the tetravalent selenium and the hexavalent selenium contained in the waste water;
The other part of the waste water is extracted and supplied to a solution containing the organic reducing agent supplied from the organic reducing agent supply unit, the acid supplied from the first acid supply unit, and the photocatalyst, and ultraviolet light is supplied. A selenium reducing unit that irradiates and reduces the hexavalent selenium and the tetravalent selenium contained in the waste water to metal selenium or hydrogen selenide;
The tetravalent selenium or the metal selenium supplied from the selenium separation unit and the selenium reduction unit is selenized by the acid supplied from the second acid supply unit and the reducing agent supplied from the reducing agent supply unit. A selenium hydrogenation unit that reduces to hydrogen;
The hydrogen selenide reduced in the selenium hydrogenation part is analyzed, the concentration of the tetravalent selenium contained in the waste water, and the total selenium of the tetravalent selenium and the hexavalent selenium contained in the waste water. A selenium analyzer having a selenium analyzer for measuring concentration. In claim 1,
The selenium analyzer is an ion exchange separation column for separating the tetravalent selenium and the hexavalent selenium in the waste water. In claim 1 or 2,
The selenium analyzer is characterized in that the photocatalyst is any one of titanium dioxide, tungsten trioxide, platinum-supported titanium dioxide, or a combination thereof. In any one of Claims 1 thru | or 3,
The selenium analyzer is characterized in that the organic reducing agent is any one of formic acid, acetic acid, oxalic acid, citric acid, methanol, ethanol, glycol, phenol, or a combination thereof. In any one of Claims 1 thru | or 4,
The selenium analyzer is characterized in that the acid is any one of nitric acid and hydrochloric acid, or a combination thereof. In any one of Claims 1 thru | or 5,
The selenium analyzer is characterized in that the ultraviolet light is light having a wavelength of 300 to 400 nm. In any one of Claims 1 thru | or 6,
The selenium analyzer, wherein the reducing agent is sodium borohydride. In any one of Claims 1 thru | or 7,
The selenium analyzer is a hydride generation-plasma emission spectrometer or hydride generation-atomic absorption spectrometer that analyzes selenium concentration with high sensitivity. In any one of Claims 1 thru | or 8,
The selenium analysis unit includes a control device that quantifies the concentration of the hexavalent selenium from the measured concentration of the tetravalent selenium and the total selenium concentration of the tetravalent selenium and the hexavalent selenium. Selenium analyzer. Collect wastewater containing tetravalent and hexavalent selenium,
A part of the waste water is separated from the tetravalent selenium and the hexavalent selenium contained in the waste water using an ion exchange separation column, and the separated tetravalent selenium is supplied to the solution from an acid and a reducing agent. And reducing to hydrogen selenide, measuring the concentration of tetravalent selenium,
The other part of the waste water is supplied to a solution composed of an organic reducing agent containing a photocatalyst and an acid and irradiated with ultraviolet light, and the hexavalent selenium and the tetravalent selenium contained in the waste water are converted into metal selenium or Reduce to hydrogen selenide, measure the total selenium concentration of the tetravalent selenium and the hexavalent selenium,
A method for fractionating and determining selenium, comprising determining the concentration of hexavalent selenium from the concentration of total selenium and the concentration of tetravalent selenium. In claim 10,
The selenium fractionation and quantification method, wherein the photocatalyst is any one of titanium dioxide, tungsten trioxide, platinum-supported titanium dioxide, or a combination thereof. In claim 10 or 11,
The organic reducing agent is any one of formic acid, acetic acid, oxalic acid, citric acid, methanol, ethanol, glycol, phenol, or a combination thereof. In any one of claims 10 to 12,
The selenium fractionation quantitative method, wherein the acid is any one of nitric acid and hydrochloric acid, or a combination thereof. In any one of claims 10 to 13,
The method for fractionating and determining selenium, wherein the ultraviolet light is light having a wavelength of 300 to 400 nm. In any one of Claims 10 thru | or 14,
The method for fractionating and determining selenium, wherein the reducing agent is sodium borohydride. In any one of Claims 10 thru | or 15,
A selenium fractionation and quantification method characterized by analyzing selenium concentration using a hydride generation-plasma emission spectrometer or a hydride generation-atomic absorption spectrometer.

Images