KR100403147B1 - Method and device for measuring the level of Nitrogen Oxide's in the environmental air or exhausted gas by colorimetry - Google Patents

Abstract

The present invention relates to a method for measuring nitrogen oxide (NO _X ) contained in the atmosphere or exhaust gas, and an apparatus for performing the method, and reacts with nitrogen oxide (NO ₂ ) to measure the amount of nitrogen oxide. A filter paper sensor 111 coated with a reagent to be developed, a sensor holder 110 for supporting the filter paper sensor at the center, a photodiode 121 for irradiating light of a predetermined wavelength to the filter paper sensor 111, and The photodiode 122 for measuring the remaining light absorbed by the filter paper sensor 111 has a space in which gas can be diffused therein, and the gas is supplied from the supply pipe 123 and the internal space for supplying gas to the internal space. From the photodiode 122 of the measuring unit 100 and the electrical measuring unit 100 consisting of a main body 120 consisting of a discharge pipe 124 for removal, a housing 130 formed with a lid for embedding the main body Specified nitrogen oxides (NO _X), the display 200 and the nitrogen oxides consisting of a display 220 for displaying the amplified signal by the amplifier 210 and the amplifier 210 for amplifying the signal related to the amount of (NO _X is a colorimetric method characterized by comprising a discharge unit 300 composed of a flow meter 310 and a pump 320 for introducing a gas containing the _X into the measuring unit 100 and discharged from the measuring unit 100 Provided is an apparatus for measuring nitrogen oxides (NO _x ) in an atmosphere or exhaust gas used.

Description

Measurement method and measurement method of nitrogen oxide in the atmosphere or exhaust gas using colorimetric method {Method and device for measuring the level of Nitrogen Oxide's in the environmental air or exhausted gas by colorimetry}

The present invention relates to a method for measuring nitrogen oxides (NO _X ) contained in the atmosphere or exhaust gas, and an apparatus for performing the method, and more particularly, to nitrous oxide contained in the nitrogen oxide contained in the atmosphere or exhaust gas. The present invention relates to a method for measuring nitrogen and nitric oxide (NO ₂ ) separately, and an apparatus thereof.

Nitrogen oxides (NO _X ) emitted from automobile engines or various combustion apparatuses are major pollutants that cause environmental pollution such as photochemical smog and acid rain, and also have serious adverse effects on the human body.

Therefore, there are many studies in progress in order to reduce the nitrogen oxides (NO _X) contained in the atmosphere, the concentration of nitrogen oxides included in order to support the research in the atmosphere or exhaust gas to reduce nitrogen oxides (NO _X) Accurate measurement is very important.

There a measuring device applied to a number of techniques have been developed being actually used for measurement of the nitrogen oxides (NO _X), as a representative example of using a device with optical gas sensor (optical gas sensor) using the chemiluminescence (chemiluminescence) An example is a device.

Although devices using chemiluminescence have high accuracy and sensitivity to nitrogen oxides, they are expensive and sensitive to the external environment, so they cannot be used conveniently in the industrial field except for professional laboratory level measurement. have.

Optical gas sensors include copper phthalocyanine (DG Zhu and MC Petty, Sensors and Actuators B, 2: 265-269, 1990), lead phthalocyanine (KF Schoch, Jr. and TA Temofonte, Thin Solid Films). 165: 83-89, 1988), squarylium dye (M. Furuki et al., Thin Solid Films, 180: 193-198, 1989), and porphyrin (MG Baron and R. Narayanaswamy, Langmuir-Blodgett films such as Sensors and Actuators B, 11: 195-199, 1993), are methods for detecting nitrogen oxides by detecting changes in light intensity.

However, these methods are not only complicated in the membrane manufacturing process but also sensitive to nitric oxide (NO ₂ ) but have difficulty in detecting nitrous oxide (NO). In addition, the tapes (N. Nakano, Analytica Chimica Acta, 321: 41-45) , 1996), media (Y. Yanagisawa and H. Nishimura, Environment International, 8: 235-242, 1982) or tubes (ED Palmes et al., Am. Ind. Hyg. Assoc. J., 37: 570-577 , 1976) and other methods of collecting nitrogen oxides in the field using various types of portable collectors and detecting them using colorimetric methods in the laboratory. However, there is a disadvantage in that the concentration cannot be monitored in real time in the field.

Recently, after applying a reagent capable of reacting with nitric oxide (NO ₂ ) on porous glass and measuring the degree of discoloration, it is possible to monitor the concentration of nitric oxide (NO ₂ ) at the ppb level in the field. Research is being actively conducted (T. Ohyama et al., Sensors and Actuators B, 64: 142-146, 2000; YY Maruo et al., Sensors and Actuators B, 57: 135-141, 1999) . This also has a big disadvantage that it is limited to the measurement of nitric oxide (NO ₂ ) and nitrous oxide (NO) cannot be measured.

In addition, various types of indicators, such as those disclosed in U.S. Patent No. 4,946,649 and U.S. Patent No. 4,904,449, which are portable and can easily measure the concentration of nitrogen oxides in the industrial field, are commercially available. As a result, they are relatively inaccurate and have been developed for one-time use, which has problems in reproducibility and inability to measure ppb levels.

In other words, as described above, it is necessary to develop a measuring apparatus with all conditions that can continuously and accurately monitor the concentration of nitrous oxide (NO) and nitrogen oxide (NO ₂ ) at the same time at a low cost easily. a situation that not see a significant progress since the technical difficulties, one it last in the field using a colorimetric method ppb level of the device that can continuously monitor the NOx have been developed to yet a nitrogen oxide in the function (NO ₂ ) Is limited to the detection of).

The present invention can continuously and accurately monitor the concentration of ppb level nitrous oxide (NO) and nitrogen oxide (NO ₂ ) at the same time at a relatively low cost, and easily at the industrial site, ppb level of nitrous oxide (NO) and nitrogen oxide. An object of the present invention is to provide a method and a device capable of accurately and simultaneously analyzing (NO ₂ ) gas.

1 is a schematic diagram for schematically illustrating the apparatus of the present invention

2 is an exploded perspective view of an embodiment of a coupling relationship between a main body and a sensor holder;

3 is a cross-sectional view for explaining a detection unit.

Figure 4 is a cross-sectional view of the laminated state shown in one embodiment of the filter paper sensor

5 is a graph showing the change in absorbance for each light wavelength

6 is a calibration curve for nitrogen oxide (NO ₂ ) measured by the present invention

7 is a cross-sectional view of a laminated state of the filter paper sensor according to another embodiment

<Explanation of symbols for the main parts of the drawings>

100: measuring unit 110: sensor holder

111 filter paper sensor 112 elastic hinge

113: support frame 114: airtight ring

115: gas diffusion hole 116: settling groove

117: bolt 118: insertion hole

120: main body 121: photodiode

122: photodiode 123: supply pipe

124: discharge pipe 125: holder seat hole

126: airtight member 127: space

128: diode support 130: housing

131 hinge 132 lid

200: display unit 210: amplifier

220: indicator 300: discharge part

310: flow meter 320: pump

In order to achieve the above object, the present invention provides a filter paper sensor 111 and a filter paper sensor 111 coated with a reagent that reacts with nitrogen oxide (NO ₂ ) in order to measure the amount of nitrogen oxide. Sensor holder 110 to be positioned to support the photodiode (LED) 121 for irradiating light of a predetermined wavelength to the filter paper sensor 111, a photo for measuring the light absorbed by the filter paper sensor 111 The main body 120 including a supply pipe 123 for supplying gas to the internal space and a discharge pipe 124 for removing gas from the internal space, in which a diode 122 is formed and a space in which gas can be diffused is formed. For amplifying a signal relating to the amount of nitrogen oxides (NO _X ) measured from the photodiode 122 of the measuring unit 100 and the electrical measuring unit 100 formed of a housing 130 having a lid having a main body therein. Amplifier (210) The amplifier display section 200 and the nitrogen oxides (NO _X) introduced into the measuring unit 100, the gas and also the measurement unit 100 containing consisting of indicator 220 for displaying the amplified signal by 210 It can be achieved by providing a measuring device consisting of a discharge unit 300 consisting of a flow meter 310 and a pump 320 for discharge from the.

Hereinafter, the measuring apparatus of the present invention will be described in more detail with reference to FIGS. 1 to 4, which are illustrated as an example, but the apparatus of the present invention is not limited to the illustrated contents.

1 is a schematic view for explaining the apparatus of the present invention, the air or exhaust gas supplied through the supply pipe 123 of the measuring unit 100 is the flow rate by the flow meter 310 of the discharge unit 300 This is confirmed and adjusted, by the operation of the pump 320 is to be introduced into the body 120 by the pressure-reducing action of the discharge pipe 124.

Gas introduced into the main body 120 is delayed in the main body 120 for a predetermined time, and diffuses into the filter paper sensor (not shown in FIG. 1) 111 mounted on the sensor holder 110. Nitrogen oxide (NO ₂ ) in the gas reacts with the reagent of the filter paper sensor 111 to discolor the filter paper sensor 111, and part of the light emitted from the photodiode 121 not shown in FIG. Absorbed by the discolored filter paper sensor 111, the absorbed light is detected by the photodiode 122.

The signal generated by the amount of light detected by the photodiode 122 is amplified by the amplifier 210 of the display unit 200 and sent to the display 220 to display the detected amount.

2 is an exploded perspective view of an embodiment for explaining a coupling relationship between the main body 120 and the sensor holder 110.

The main body 120 has a supply pipe 123 for supplying gas and a discharge pipe 124 for discharging the gas, and an upper portion thereof in FIG. 2 for measuring nitrogen oxides (NO _X ) contained in the gas. Holder mounting hole 125 for inserting and withdrawing the sensor holder 110, which is not shown filter paper sensor 111 is shown is formed, and both sides have a constant wavelength on one side on the same line as the filter paper sensor 111 The photodiode 121 for projecting light is mounted, and on the other side, a photodiode 122 is mounted for measuring the remaining light absorbed by the filter paper sensor 111 of the light projected from the photodiode 121.

The sensor holder 110 is coupled by a pair of support frames 113 for supporting the filter paper sensor 111 and an elastic hinge 112 for elastically operating the pair of support frames 113, A gas diffusion hole 115 is formed in the center of the pair of support frames 113 to easily diffuse the gas into the filter paper sensor 111, and the diffusion of the gas may be diffused only by the gas diffusion hole 115. An airtight ring 114 is installed in order to be able to make it possible. Insertion hole 118 of the bolt 117 is formed in the lower portion of the frame 113, it is possible to maintain a tighter tightness by tightening the bolt 117.

3 is a cross-sectional view of the detector 100 for illustrating a state in which the main body 120 is seated in the housing 130 and the sensor holder 110 in which the filter paper sensor 111 is mounted is coupled with the main body. 130 has a lid 132 coupled by a hinge 131 to open and close the top to facilitate mounting and detachment of the filter paper sensor before and after the measurement of nitrogen oxide (NO _X ), the lid 132 ) Will act as a darkroom when closed.

As described above, the main body 120 mounted in the housing 130 has a space 127 through which exhaust gas and the like can flow, and the side wall of the main body 120 has airtightness by the diode support 128. The photodiode 121 and the photodiode 122 coupled to each other are held.

In addition, the sensor holder 110 equipped with the filter paper sensor 111 has the filter paper sensor 111 of the photodiode 121 and the photodiode 122 through the holder mounting hole 125 formed in the main body 120. It is fitted to be placed therebetween, and at this time, the inside and the outside of the sensor holder 110 and the holder mounting hole 125 is blocked by the airtight member 126 so as not to leak the internal exhaust gas.

The present invention provides a method for measuring nitrous oxide (NO) and nitric oxide (NO ₂ ) by the following method using a measuring device having the above structure.

Nitric oxide (NO ₂₎ with the oxidation of by reaction dried by immersing the filter paper in the reagents to be the discoloration reaction of nitrogen (NO ₂₎ to measure the filter paper for the manufacturing stage of the filter paper sensor and a nitrogen oxide (NO ₂₎ with, by reaction discoloration reaction The filter paper was immersed in the reagent to be dried, and the oxidant was applied to a separate filter paper to prepare nitrous oxide (NO) oxidation filter paper, and attached to both sides of the prepared measurement paper for measuring nitrogen oxide (NO ₂ ). _X ) preparing a filter paper sensor for measurement; Fixing each of the manufactured filter paper sensors to keep the airtightness in the sensor holder; Placing each sensor holder having the filter paper sensor fixed thereon in the main body through an insertion hole formed in an upper part of the main body; Introducing a gas containing nitrogen oxides (NO _X ) into the interior of the body by adjusting the suction power of the pump and the flow meter into the interior of each body where each sensor holder is mounted; Waiting for the nitrogen oxide (NO _X ) containing gas to be sufficiently diffused in the filter paper sensor; Projecting light from photodiodes having a certain wavelength mounted on each main body to each filter paper sensor discolored by diffusion of nitrogen oxide (NO _X ) -containing gas, and the remaining light absorbed by each filter paper sensor to the opposite side of the photodiode Measuring each absorbance through a mounted photodiode; Determining the contents of nitrogen oxides (NO ₂ ) and nitrogen oxides (NO _X ) by comparing the measured absorbance with a previously prepared calibration curve; A method for measuring nitrous oxide (NO) and nitrogen oxides (NO ₂ ) comprising the step of determining the amount of nitrous oxide (NO) by the difference in the content of nitrogen oxides (NO ₂ ) and nitrogen oxides (NO _X ) to provide.

As a coloration reagent which is applied to the filter paper sensor and reacts with nitric oxide (NO ₂ ) to develop color, 2,5-bis (4-aminophenyl) -1,3,4-oxadiazole (2,5- bis (4-aminophenyl) -1,3,4-oxadiazole), 3,3'-dimethylbenzidine, called o-tolidine, sulfanilamide, N, N-dimethyl-1-naphthylamine (N, N'-diphenylbenzidine) may be used and oxidizes nitrous oxide (NO). As an oxidizing agent for oxidizing with nitrogen (NO2), chromium trioxide is mentioned.

Illustrating a method of making a filter paper sensor using the above-described colorizing reagent and oxidizing agent, after removing water or other volatile components in the filter paper to be manufactured by the sensor and immersed in a solution of the coloring reagent prepared at a certain concentration After taking out and drying sufficiently, a filter paper sensor for nitric oxide (NO ₂ ) reaction is prepared, and the untreated filter paper is positioned on both sides of the filter paper sensor manufactured by the method as described above, as shown in FIG. 4. A filter paper coated with an oxidizing agent is placed outside of it to oxidize nitrogen oxide (NO _X ), that is, nitrous oxide (NO), to nitrogen oxide (NO ₂ ) to simultaneously measure nitrous oxide (NO) and nitrogen oxide (NO ₂ ). To produce a filter paper sensor.

The filter paper sensor manufactured by the above method may be discolored by nitrous oxide (NO) and nitric oxide (NO ₂ ) or natural light contained in the air, so it should be manufactured by darkroom work. In order to prevent discoloration by nitrous oxide (NO), nitric oxide (NO ₂ ) and natural light, it is necessary to airtight packaging.

In order to identify the wavelength of the light that can detect the color change most sensitively by the measuring device and method as described above, the coloration reagent uses o-tolidine and chromium trioxide as the oxidizing agent. A filter paper sensor was manufactured as follows.

As a substrate of the coloration reagent, commercially available commercial laboratory filter paper was used, and after treatment in a hot air dryer to remove water or other contaminants in the filter paper, 5 g of o-tolidine per 1 liter of ethanol. The solution for preparing a sensor having a concentration of was prepared by stirring well at room temperature, and the filter paper was immersed for about 5 minutes, and then dried in a vacuum dryer at room temperature for about 30 minutes to darken the filter paper sensor for nitric oxide (NO ₂ ). It was prepared by.

Apart from the above, an oxidant solution having a concentration of 50 g chromium trioxide per liter of distilled water was prepared, the filter paper was immersed for 5 minutes, and then dried in a vacuum dryer at room temperature for about 3 hours. After the coated filter paper was prepared, untreated filter paper was placed on both sides of the filter paper sensor for nitric oxide (NO2) prepared above, and the color of the filter paper was discolored by nitrous oxide (NO) and nitric oxide (NO ₂ ). As shown in FIG. 5, the filter paper sensor was manufactured and measured for each light wavelength using the filter paper sensor and the untreated filter paper. As a result, it was confirmed that the light wavelength was optimal at 430 nm.

In addition, by using the filter paper sensor for nitric oxide (NO ₂ ) prepared above and the apparatus of the present invention measured by varying the concentration of nitric oxide (NO ₂ ) at a wavelength of 430 nm and the calibration curve using the results shown on the display As a result, the calibration curve as shown in FIG. 6 was obtained.

As can be seen from FIG. 6, the calibration curve shows a linear proportion as y = 0.207x and R ² = 0.9209 when the absorbance is y and the concentration of nitric oxide (NO ₂ ) is x.

As described above, nitrogen oxides (NO _x ) and nitrogen oxides (NO ₂ ) are measured by using two measurements or two devices to calculate the amount of nitrous oxide (NO) to obtain nitrous oxide (NO) and nitrogen oxides ( NO ₂ ), or by manufacturing a filter paper sensor as shown in Fig. 7 and mounting it in the sensor holder to inject exhaust gas once and then separate and measure the sensor at the same time from the same exhaust gas Nitrous oxide (NO) and nitric oxide (NO ₂ ) can also be measured.

That is, the filter paper sensor as shown in FIG. 7 is mounted on the sensor holder 110, and the pump 320 is operated to allow a certain amount of exhaust gas to enter the inside of the main body 120. NO ₂ ) causes discoloration of the outermost chromophoric reagent layer, and nitrous oxide (NO) does not react in the outermost chromophoric reagent layer but diffuses inside and passes through the oxidant treatment layer to react with the oxidant to react with nitrous oxide ( As NO) is changed to nitric oxide (NO ₂ ), it diffuses inside and discolors the colorization reagent layer located at the center.

After sufficient diffusion, the sensor holder 110 is removed from the main body 120 in the dark room, and the filter paper sensor 111 is separated from the sensor holder 110. Then, the outermost layer of the colorization reagent layer and the center of the colorization reagent layer are removed. When the light absorbance of each light is measured in the state of being mounted on the sensor holder 110 and inserted into the main body 120, the nitrous oxide (NO) and the nitric oxide (NO ₂ ) may be respectively measured.

In this case, the calibration curve can be efficiently used if a standard gas containing nitrous oxide (NO) and nitrogen oxide (NO ₂ ) is produced and prepared in advance.

As it described above, it is possible to measure the NO and NO ₂ concentrations in the ppb level contained in the air or exhaust gas by the measuring apparatus and method of the present invention at the same time with high sensitivity, and successively without directly before and after the test process in the field As a result, it is possible to monitor the concentration of nitrogen oxide so that it is always portable and can be applied in the field, and the structure and parts are relatively simple compared to the detection performance, so the measurement cost is low.

Therefore, the measuring device of the present invention can be applied to detect nitrogen oxide at low cost in various industrial fields.

Claims (7)

In order to measure the amount of nitrogen oxides, a filter paper sensor 111 coated with a reagent that reacts with nitrogen oxide (NO ₂ ), a sensor holder 110 for supporting the filter paper sensor at a center, and the filter paper sensor ( The photodiode 121 for irradiating light of a predetermined wavelength to the 111, the photodiode 122 for measuring the light remaining after absorbed from the filter paper sensor 111 is formed a space in which gas can be diffused Measurement unit consisting of a main body 120 consisting of a supply pipe 123 for supplying gas into the inner space and a discharge pipe 124 for removing gas from the inner space, and a housing 130 having a lid incorporating the main body ( 100 and an amplifier 210 for amplifying a signal relating to the amount of nitrogen oxides (NO _X ) measured from the photodiode 122 of the electrical measuring unit 100 and a signal amplified by the amplifier 210 are displayed. doing One indicator 220 is a display 200 and the NOx flow meter 310 and a pump 320 for discharging from (NO _X), the measuring section 100, and also measuring unit 100, introduced into the gas containing the consisting of A device for measuring nitrogen oxides (NO _x ) in the atmosphere or exhaust gas using a colorimetric method, characterized in that consisting of a discharge unit 300 consisting of. The method according to claim 1, the sensor holder 110 by a pair of support frame 113 for supporting the filter paper sensor 111 and the elastic hinge 112 for elastically operating the pair of support frame 113. The gas diffusion hole 115 is formed in the center of the pair of supporting frames 113 to easily diffuse the gas into the filter paper sensor 111, and the gas diffusion hole 115 is used to diffuse the gas. An airtight ring 114 is installed to allow only diffusion, and a seating groove 116 is formed to accurately determine the position of the airtight ring 114, and secures airtightness by the airtight ring 114. In the lower portion of the support frame 113, the insertion hole 118 of the bolt 117 is formed to tighten the bolt 117, the atmosphere using the colorimetric method characterized in that it is configured to maintain a more tight airtight Device for measuring nitrogen oxides (NO _x ) in exhaust gas. The nitrogen in the atmosphere or exhaust gas using the colorimetric method according to claim 1 or 2, wherein the photodiode 121 for irradiating the filter paper sensor 111 with light having a predetermined wavelength is a photodiode having a wavelength of 430 nm. Measuring device for oxide (NO _x ). Nitric oxide (NO ₂₎ the nitrogen oxide to deposition by drying the filter paper to the reagents to be the discoloration reaction by the reaction of (NO ₂₎ manufacturing step and a nitrogen oxide of the measuring filter (NO ₂₎ reagents for the color change reaction by the reaction of The filter paper was immersed in and dried, and an oxidizing agent was applied to a separate filter paper to prepare nitrous oxide (NO) oxidation filter paper, and attached to both sides of the prepared nitric oxide (NO ₂ ) measurement paper to measure nitrogen oxides (NO _X ). Preparing a filter paper sensor; Fixing each of the manufactured filter paper sensors to keep the airtightness in the sensor holder; Placing each sensor holder having the filter paper sensor fixed thereon in the main body through an insertion hole formed in an upper part of the main body; Introducing a gas containing nitrogen oxides (NO _X ) into the interior of the body by adjusting the suction power of the pump and the flow meter into the interior of each body where each sensor holder is mounted; Waiting for the nitrogen oxide (NO _X ) containing gas to be sufficiently diffused in the filter paper sensor; Projecting light from photodiodes having a certain wavelength mounted on each main body to each filter paper sensor discolored by diffusion of nitrogen oxide (NO _X ) -containing gas, and the remaining light absorbed by each filter paper sensor to the opposite side of the photodiode Measuring each absorbance through a mounted photodiode; Determining the contents of nitrogen oxides (NO ₂ ) and nitrogen oxides (NO _X ) by comparing the measured absorbance with a previously prepared calibration curve; Determining the amount of nitrous oxide (NO) by the difference in the content of nitrogen oxides (NO ₂ ) and nitrogen oxides (NO _X ) nitrogen oxides in the atmosphere or exhaust gas using the colorimetric method (NO _x) Measurement method of). The coloring agent which is applied to the filter paper sensor and reacts with nitric oxide (NO ₂ ) to develop a color is 2,5-bis (4-aminophenyl) -1,3,4-oxadiazole (2, 5-bis (4-aminophenyl) -1,3,4-oxadiazole), 3,3'-dimethylbenzidine, called o-tolidine, sulfanilamide ), N, N-dimethyl-1-naphthylamine (N, N-dimethyl-1-napthylamine, N, N'-diphenylbenzidine) is selected using a colorimetric method characterized in that Method for measuring nitrogen oxides (NO _x ) in the atmosphere or exhaust gas. The chromophoric reagent according to claim 5, which is applied to the filter paper sensor and reacts with nitric oxide (NO ₂ ) to develop a color, is 3,3'-dimethylbenzidine (3,3'-) called o-tolidine. Nitrogen oxide (NO _x ) in the atmosphere or exhaust gas using a colorimetric method characterized in that it is dimethylbenzidine). The colorimetric method according to any one of claims 4 to 6, wherein the oxidizing agent for oxidizing nitrous oxide (NO) contained in the gas to nitric oxide (NO ₂ ) is chromium trioxide. Method for measuring nitrogen oxides (NO _x ) in the atmosphere or exhaust gas.