KR20070044898A - System for measuring hydrogen peroxide and measuring method - Google Patents

Abstract

The present invention relates to a method and a measuring system for measuring hydrogen peroxide, using Fe ³⁺ -EDTA which is very stable in a small amount of hydrogen peroxide in the atmosphere and in the water at room temperature, and photocatalytic reaction of the complex Fe ³⁺ -EDTA. It provides a method and measuring system for measuring hydrogen peroxide comprising the step of stably reacting the reduced Fe ²⁺ -EDTA with hydrogen peroxide to produce radicals, formed by reaction with radicals using terephthalic acid, isomers The present invention provides a reliable method and system for measuring hydrogen peroxide by producing pure terephthalic acid without oxygen.

Hydrogen peroxide, iron (III) -ideti, terephthalic acid

Description

System for Measuring hydrogen peroxide and Measuring method

1 is a view showing a measurement system of hydrogen peroxide according to the present invention,

Figure 2 shows a reduction reactor of the measurement system of hydrogen peroxide according to the present invention,

Figure 3 is a graph showing the rate of Fe ³⁺ -EDTA is reduced to Fe ²⁺ -EDTA under ultraviolet irradiation according to an embodiment of the present invention.

4 is a view showing a bubble removing unit of the measurement system of hydrogen peroxide according to the present invention,

5 is a view showing a measurement result of the signal strength according to the known hydrogen peroxide concentration according to an embodiment of the present invention.

** Description of the main symbols in the drawings **

1: solution carrier 2: reduction reactor

3: chemical reactor 4: amplification reactor

5: Fluorescence Detector 6: Bubble Remover

21: inlet 22: outlet

23: coiled tube 24: ultraviolet lamp

25: cooling fan

The present invention relates to a method and a measurement system for measuring hydrogen peroxide.

Hydrogen peroxide is a trace gas component in the atmosphere produced by photochemical reactions and is used as a direct or indirect indicator of the oxidation capacity of the atmosphere. Hydrogen peroxide forms acid rain by chemical reaction with sulfur oxides and nitrogen oxides in the air, and this acid rain has toxic effects on plants. Representative adverse effects of acid rain include deforestation in Western Europe and Eastern America, which are well known.

In addition, hydrogen peroxide is used for water treatment, and its use is increasing gradually in recent years. Hydrogen peroxide, for example, also generates radical hydroxides, which are powerful oxidants for treating pollutants in water in advanced oxidation processes, and the radicals produced are very important species in the oxidation and treatment of pollutants. However, a small amount of hydrogen peroxide in water has been reported to cause serious damage to the human body, in Germany, the concentration of hydrogen peroxide remaining in the treated water is regulated to 0.1 mg / L.

Therefore, considering that hydrogen peroxide has been recognized as a pollutant that is an indicator of photochemical reaction as a trace gas in the atmosphere, and that hydrogen peroxide has been recognized as a means of treating pollutants in the water treatment field, Measurement is very important.

Various conventional methods of analyzing hydrogen peroxide have already been analyzed by Schick et al., Water Research (1997, 31, pages 1371-1378) and Kosaka et al. Environmental Science and Technology (1998, 32, 32, 3821-3824). ), Which is briefly summarized below.

Previously developed methods of measuring hydrogen peroxide include iodide titration, photometric analysis, fluorometric analysis using peroxidase, an enzyme that catalyzes the oxidation of p- hydroxyphenylacetic acid in the presence of hydrogen peroxide, Various hydrogen peroxides such as potassium titanium oxalate, DMP method (2,9-dimethyl-1,10-phenanthroline), and DPD method (peroxidase catalyzed oxidation of N, N-diethyl-p- phenylendiamine) Analytical methods are known.

Among the hydrogen peroxide assays described above, fluorescence spectrometry has been mainly used for the analysis of trace amounts of hydrogen peroxide, but fluorescence spectroscopy should be shaded because the peroxidase enzyme is unstable in light exposure and room temperature. Lower refrigeration is required. In addition, the enzymes used in fluorescence assays are very expensive.

In addition, the above-described conventional methods of analyzing hydrogen peroxide may be greatly influenced by disturbing components such as chlorine and ozone, and in particular, the waste liquid generated because the DMP method uses copper (Cu ²⁺ ) component is very environmentally friendly. It can be said to be harmful. Iodide titration, photometric analysis, potassium-titanium-oxalate method, DMP method, and DPD method are known as hydrogen peroxide methods with low sensitivity. As a result, conventional hydrogen peroxide measurement methods have a high cost and have a lower sensitivity due to the change in the biochemical activity of reaction reagents used in various environments.

As an alternative, one may consider using a reaction mechanism for reacting a Fenton reaction, divalent iron ions (Fe ²⁺ ) with hydrogen peroxide to form reactive radical hydroxides. Hydroxide radicals formed at this time can be measured by using a fluorescence detector for hydroxybenzoic acid (hydroxybenzoic acid) formed by reaction with benzoic acid (benzoic acid). However, the benzoic acid hydroxide formed forms three isomers, ortho, meta, and para-benzoic acid hydroxides, but it is difficult to simultaneously analyze the three isomers with the present technology. The reason is that these three isomers differ in the excitation wavelength and emission wavelength of fluorescent emission.

In addition, the divalent iron ion used works well only at very low pH 1.8 and easily changes to Fe (OH) ₃ , a very dark brown iron oxide when stored under the above pH conditions. it's difficult. Therefore, this method makes it difficult to quantitatively measure the concentration of hydrogen peroxide over a long period of time.

This solves the above problems, prevents loss of samples and methods for more reliable measurement of hydrogen peroxide, which is present in trace amounts in the atmosphere and water, and eliminates unnecessary processes from sampling to analysis. There is an urgent need to develop an analytical system that can be achieved.

Accordingly, the present invention is to solve the problems of the above-described method of measuring hydrogen peroxide, Fe ^{3 +} -EDTA which is present in a very stable at room temperature conditions of hydrogen peroxide present in a trace amount in the air and water phase, Fe ³ complex ^It is an object of the present invention to provide a method and measuring system for measuring hydrogen peroxide comprising the step of stably reacting Fe ²⁺ -EDTA and hydrogen peroxide reduced by photodegradation with -EDTA to generate radicals.

In addition, an object of the present invention is to provide a highly reliable method for measuring and measuring hydrogen peroxide by forming terephthalic acid and reacting with radicals to produce pure terephthalic acid.

In addition, an object of the present invention is to provide an analysis system capable of performing batch real-time analysis by eliminating unnecessary processes from sampling to analysis.

Hereinafter, a hydrogen peroxide measuring system and a measuring method according to the present invention will be described in detail with reference to the accompanying drawings.

In the hydrogen peroxide measurement system according to the present invention, a chemical reactor for forming terephthalic acid by reacting a solution containing radical hydroxide formed by reacting divalent iron ions (hereinafter, Fe ²⁺ ) and hydrogen peroxide with terephthalic acid (Terephthalic acid) And a fluorescence detector for measuring the fluorescence intensity of the terephthalic acid hydroxide.

The chemical reactor may include a primary reactor for reacting a solution containing Fe ²⁺ and hydrogen peroxide to form a radical, and a secondary reactor for reacting the radical formed with terephthalic acid to form terephthalic acid. . In addition, the chemical reactor may further include an injection hole for injecting a solution containing sodium hydroxide or trivalent aluminum (hereinafter, Al ³⁺ ) ions.

Alternatively, the hydrogen peroxide measurement system may further include an amplification reactor for mixing the formed solution containing terephthalic acid and sodium hydroxide or Al ³⁺ .

The chemical reactor or amplification reactor may be provided with a bubble removing portion on the top and may be provided with a plurality of bubble discharge port.

1 is a block diagram of a hydrogen peroxide measurement system according to an embodiment of the present invention. As shown, it comprises a solution carrier (1), reduction reactor (2), chemical reactor (3), amplification reactor (4), fluorescence detector (5), bubble removing unit (6). Although the above components are not limited, it is preferable that the reaction proceeds in an organically connected reaction solution. That is, the outlets of the reduction reactor 2 and the solution carrier 1 are respectively connected to one inlet of the chemical reactor 3, the outlet of the chemical reactor is connected to the inlet of the amplification reactor, and the outlet of the amplification reactor is the fluorescence detector. It is preferable that the reaction and the detection proceed in connection with the flexible flow of the reaction solution.

The solution carrying part 1 serves to provide the chemical reactor 3 with various reagents necessary for measuring hydrogen peroxide and hydrogen peroxide. The hydrogen peroxide may be collected in the atmosphere or in an aqueous solution containing hydrogen peroxide. The solution conveying unit 1 preferably uses a PTFE (Polytetrafluoroethylene) connection line and a pump suitable for various chemical reactions.

The reduction reactor 2 serves to supply Fe ²⁺ to the chemical reactor by reducing Fe ³⁺ to Fe ²⁺ . Although not limited, the Fe ²⁺ is iron (II) -ethylenediaminetetraacetic acid (hereinafter referred to as Fe (III) -ethylenediaminetetraacetic acid (hereinafter referred to as Fe ³⁺ -EDTA)) complex which is very stable at room temperature. , Fe ²⁺ -EDTA).

2 is a view showing a reduction reactor 2 of the hydrogen peroxide measurement system according to an embodiment of the present invention. A solution containing Fe ³⁺ such as Fe ³⁺ -EDTA is transferred to a quartz (not limited) reduction reactor, which is irradiated with Fe ²⁺ such as Fe ²⁺ -EDTA by irradiation with an ultraviolet wavelength of 254 nm to 400 nm. It goes through a reduction process and immediately meets and mixes with hydrogen peroxide.

Although not limited, as shown in FIG. 2, the reduction reactor 2 is preferably in the shape of a tube, and in order to increase the efficiency of the reduction reaction, it is preferable that the reduction tube 2 be a coiled tube 23 in which all or a part of the tube proceeds in the direction of ultraviolet irradiation. Do. That is, it takes the form of an external shape coil, and is comprised so that the irradiation area of the ultraviolet-ray irradiated from the ultraviolet-ray lamp 24 can be increased more efficiently. The reduction reactor (2) is provided with an inlet (21) into which the sample is injected and an outlet (22) flowing out to the chemical reactor, and may further include an ultraviolet lamp and a cooling fan (25) for reducing the temperature generated during the reaction. have. If necessary, the reduction reactor may not be provided separately, but may perform the reaction of Equation 1 in-situ in the chemical reactor.

An example of the reaction occurring in the reduction reactor 2 is as follows.

In the reduction reactor, the Fe ³⁺ -EDTA solution is reduced to Fe ²⁺ -EDTA by ultraviolet irradiation as in Equation 1.

<Formula 1> hv + Fe ^{3 +} -EDTA Fe ^{2 +} -EDTA

Figure 3 shows an example in which Fe ^{3 +} -EDTA is reduced to Fe ^{2 +} -EDTA under ultraviolet irradiation. The Fe ²⁺ -EDTA formed was collected and its content was measured using a phenanthroline method using a sample of Young's UV spectrophotometer model 730D and various concentrations (0.01 to 0.1 mM) of Fe ³⁺ -EDTA at a wavelength of 510 nm. Fe ²⁺ -EDTA which is reduced by measurement is shown in FIG. 3.

Next, in the chemical reactor (3), the injected Fe ²⁺ and hydrogen peroxide contained in the air or liquid sample react to form radical hydroxide, and the radical reacts with a solution containing terephthalic acid. It forms terephthalic acid hydroxide.

As an example, as shown in Equation 2, hydrogen peroxide is reacted with reduced Fe ²⁺ -EDTA to form radicals, and at the same time, terephthalic acid and radicals which are already present in the chemical reactor or injected into the chemical reactor. The reaction is carried out as in Chemical Formula 3 to form terephthalic acid hydroxide as a final product. The formed terephthalic acid does not form other isomers, so that the stable and high reliability of hydrogen peroxide concentration can be measured.

<Formula 2> Fe^{2 +}-EDTA + H₂O₂ Fe^{3 +}-EDTA + OH^- + OH

<Formula 3> OH ㅇ + terephthalic acid terephthalic acid hydroxide

The chemical reactor (3) promotes the reaction between hydrogen peroxide and reduced Fe ²⁺ -EDTA and at the same time serves to induce the generated radical hydroxide to mix well with terephthalic acid to produce terephthalic acid hydroxide. The shape is not limited, but may be tubular or flask type through which fluid can flow, and a stirring device may be provided therein. The shape of the reactor can be applied without limitation to shapes known in the art. It is preferable to maintain a sufficient residence time so that the reaction time is maintained for 30 seconds or more.

The chemical reactor 3 is divided into a primary reactor for reacting a solution containing Fe ²⁺ and hydrogen peroxide to form radicals, and a secondary reactor for reacting the radicals formed with terephthalic acid to form terephthalic acid. It may be provided.

Then, the chemical reactor 3 is preferably further provided with an injection hole (not shown) for injecting a reagent to induce a higher luminescence intensity because terephthalic acid hydroxide produced after a sufficient reaction is weak luminescence intensity by fluorescence Do. In this case, terephthalic acid hydroxide shows a very characteristic fluorescence emission characteristics, it is preferable that the following method is used to enhance the fluorescence intensity of terephthalic acid hydroxide. One is to increase the pH to 11 or more using 0.05 to 0.1 mol (M) of sodium hydroxide (NaOH), the other is 1 to 10 mol of aluminum solution (Al (NO ₃ ) _{3 ㅇ} 9H ₂ O).

Instead of the inlet, a solution containing terephthalic acid hydroxide produced after a chemical reaction connected to a chemical reactor is injected and a solution containing the injected terephthalic acid and sodium hydroxide or trivalent aluminum ions (Al ³⁺ ). It may further include an amplification reactor 4 for mixing. The shape of the amplification reactor is not limited and may apply a reactor shape capable of mixing solutions known in the art. It may be in the shape of a tube.

Meanwhile, the bubble removing unit 6 may be located at the upper portion of the chemical reactor 3 or the amplification reactor 4 or both. The microbubbles present in the solution should be removed because bubbles are formed during the mixing of the solution, and the bubbles are captured by the fluorescence detector as a signal of hydrogen peroxide and appear as a component that prevents accurate detection of hydrogen peroxide. Thus, the bubble removing unit serves to remove bubbles before the solution and the bubbles simultaneously flow into the fluorescence detector.

For example, in order to measure the hydrogen peroxide contained in the gas phase, the gaseous constituents must be dissolved in a carrier solution and converted into a liquid phase. At this time, the gas phase insoluble in the transport solution will release the outside. Of course, even when the measurement object is a liquid, since the fine bubbles are always formed in the mixing process of the solution to act as an interference component during fluorescence detection, it is preferable that the fine bubbles are removed by the bubble remover.

Figure 4 shows a bubble removing unit according to an embodiment of the present invention. The bubble removing part may be one kind of glass material (not limited), but more preferably, it is provided with a plurality of bubble discharge ports, and the size of the bubble discharge holes is preferably various.

For example, it is preferable that the first stage 61 and the second stage 62 are configured, and the first stage 61 is a tubular micro branched tube made of metal having a hole having a diameter of about 1 mm to about 2 mm. Stage 62 is a branch tube made of ordinary glass to remove coarse bubbles larger than fine bubbles. At this time, the bubbles formed are moved to the upper portion of the glass tube by gravity and move to the first and second stages, while the fine bubbles become larger and are quickly removed from the solution by buoyancy.

The fluorescence detector 5 measures the concentration of terephthalic acid hydroxide by measuring the fluorescent light emitted from the terephthalic acid hydroxide produced in the reaction process. Fluorescent detectors can be used without limitation, fluorescent detectors known in the art.

For example, the fluorescent luminescence detected by the fluorescence detector 5 causes a difference in fluorescence intensity depending on the concentration of hydrogen peroxide included in the sample. That is, as the concentration of hydrogen peroxide decreases, the magnitude of the signal decreases, while the higher the concentration of hydrogen peroxide, the larger the magnitude of the signal.

The fluorescence detector 5 may further include a signal analysis unit, and detect a known concentration of hydrogen peroxide by analyzing an electrical signal output through the emission amount detection, and set the fluorescence intensity of the initially detected fluorescent emitter to a known concentration of hydrogen peroxide. Then, the concentration of hydrogen peroxide included in the measurement object is detected by comparing the fluorescence intensity of the measurement object with the fluorescence intensity calibrated. Thereafter, the signal analyzer calculates the concentration of hydrogen peroxide included in the measurement target by comparing the fluorescence intensity of the measurement target output through the emission amount detection with the fluorescent intensity of the known hydrogen peroxide.

Figure 5 shows the results of measuring the intensity of the fluorescent light according to the concentration of hydrogen peroxide known as an embodiment according to the present invention by an electrical signal. Known hydrogen peroxide concentrations were determined by titration with KMnO ₄ . The concentration of hydrogen peroxide developed in the present invention was determined with the concentration of hydrogen peroxide determined primarily and is shown in FIG. 5.

On the other hand, the present invention provides a method for measuring hydrogen peroxide.

That is, the step of reacting a solution containing a radical and a terephthalic acid (Terephthalic acid) formed by the reaction of Fe ²⁺ and hydrogen peroxide to form terephthalic acid; And measuring the fluorescence intensity of the terephthalic acid hydroxide.

The Fe ²⁺ is, iron (Ⅲ) as mentioned above - preferably by reduction to obtain a Idi tieyi (Fe ²⁺ -EDTA) - Idi tieyi (Fe ³⁺ -EDTA) was irradiated with ultraviolet rays in the complexes of iron (Ⅱ) Do.

In addition, it is preferable to further improve the fluorescence intensity by further comprising adding sodium hydroxide or trivalent aluminum ions (Al ³⁺ ) or an aqueous solution thereof after forming terephthalic acid.

Since the method of measuring hydrogen peroxide overlaps with the description of the hydrogen peroxide measuring system, detailed description thereof will be omitted.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

The method and measuring system for measuring hydrogen peroxide according to the present invention can be usefully applied to continuous measurement as well as cost reduction as a method that can be applied simultaneously to the water quality and the atmospheric region. In particular, it uses Fe ³⁺ -EDTA, which is very stable at room temperature, to produce more stable and isomer-free pure hydroxide terephthalic acid, resulting in highly reliable measurement and eliminating unnecessary processes from sampling to analysis. Real time analysis provides the effect.

Claims (12)

A chemical reactor for forming terephthalic acid by reacting a solution containing radical hydroxide formed by reacting ^divalent iron ions (Fe ²⁺ ) and hydrogen peroxide with terephthalic acid; A hydrogen peroxide measurement system comprising a; fluorescence detector for measuring the fluorescence intensity of the terephthalic acid hydroxide. The method of claim 1, wherein the chemical reactor is connected to a reduction reactor for supplying divalent iron ions (Fe ²⁺ ) by reducing trivalent iron ions (Fe ³⁺ ) to divalent iron ions (Fe ²⁺ ). Hydrogen peroxide measurement system. 3. The hydrogen peroxide measurement system according to claim 2, wherein the reduction reactor is tubular and all or a portion of the tube is coiled in the ultraviolet irradiation direction. The method of claim 1, wherein the chemical reactor is reacted with a solution containing divalent iron ions (Fe ²⁺ ) and hydrogen peroxide to form a radical hydroxide and the radical and terephthalic acid formed by reacting the radical and the formed terephthalic acid Hydrogen peroxide measurement system, characterized in that comprises a secondary reactor to form a. The system of claim 1, wherein the chemical reactor further comprises an inlet for injecting a solution containing sodium hydroxide or trivalent aluminum (Al ³⁺ ) ions. The hydrogen peroxide measuring system according to claim 1, further comprising an amplification reactor for mixing the formed terephthalic acid and a solution containing sodium hydroxide or trivalent aluminum ions (Al ³⁺ ). The hydrogen peroxide measurement system according to any one of claims 1 to 6, wherein the chemical reactor or the amplification reactor has a bubble removing unit at the top. The system for measuring hydrogen peroxide according to claim 7, wherein the bubble removing unit has a plurality of bubble outlets and the size of the bubble outlets is multi-type. 7. The hydrogen peroxide measurement system according to any one of claims 1 to 6, wherein the divalent iron ions (Fe ²⁺ ) are in the form of iron (II) -idetiase (Fe ²⁺ -EDTA) complexes. Reacting a solution containing radical hydroxide formed by the reaction of divalent iron ions (Fe ²⁺ ) with hydrogen peroxide and terephthalic acid to form terephthalic acid; And Hydrogen peroxide measurement method comprising the; measuring the fluorescence intensity of the terephthalic acid hydroxide. The method of claim 10, further comprising adding sodium hydroxide or trivalent aluminum ions (Al ³⁺ ) or an aqueous solution thereof. The method of claim 10, wherein the divalent iron ions (Fe ²⁺ ) is irradiated with ultraviolet rays to the iron (III)-eddiey (Fe ^{3 +} -EDTA) complex iron (II)-editiy (Fe ^{2 +} -EDTA) Method for measuring hydrogen peroxide, characterized in that obtained by reducing).

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