JPH10253508A - Nitrogen oxide sampler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a nitrogen oxide sampler by performing the sampling and recovering of nitrogen oxide effectively under natural light without the need for an ultraviolet lamp in the nitrogen oxide sampler. SOLUTION: This nitrogen oxide sample is equipped with a plate-shaped base 11, on which the particles of a photocatalyst 10 are immobilized, and a plate-shaped translucent plate 14, on which external light strikes and which transmits it. The surface of the base 11 where the catalyst 10 is immobilized and the translucent plate 14 are arranged opposedly with a space to form a gas passage by the space formed by the base 11 and the translucent plate 14. By this configuration, the sampler is shaped into a plate, a window part is formed for introducing external light such as natural light into the inside, and the photocatalyst 10 is activated by the external light introduced through the window part to sampling and to recover nitrogen oxides, to eliminate the need for an ultraviolet lamp, and to implement miniaturization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sampler, and more particularly to a nitrogen oxide sampler for measuring the concentration of nitrogen oxide contained in air or indoor air.

[0002]

2. Description of the Related Art The measurement of the concentration of nitrogen oxides contained in air and indoor gases is performed by measuring occupational health, healthy housing environment, exhaust gas,
Alternatively, it is used in the monitoring field for monitoring environmental pollution and the like. Usually, in the measurement of the concentration of nitrogen oxides, the concentration of nitrogen monoxide NO and nitrogen dioxide NO ₂ is measured. Conventionally, as a method of measuring the concentration of nitrogen oxides in a gas, a chemiluminescence method utilizing the reaction of NO with ozone, a method utilizing infrared / ultraviolet absorption, or a method of chemically absorbing a certain amount of liquid to absorb the same. Methods for performing quantitative analysis and other various measurement methods are known. In addition, in order to improve the measurement accuracy when the concentration of nitrogen oxides is low, the efficiency of trapping and collecting nitrogen oxides, and the price, etc., use a diffusion scrubber to adsorb nitrogen oxides with a photocatalyst and measure the concentration. Methods have also been proposed.

FIG. 6 is a schematic view of a conventional nitrogen oxide sampler used for measuring the concentration of nitrogen oxide using a photocatalyst. In FIG. 6, a nitrogen oxide sampler 90 uses a cylindrical diffusion scrubber, and arranges a cylindrical quartz tube 92 outside the ultraviolet lamp 93 provided at the center of the cylinder so as to surround the ultraviolet lamp 93. And the quartz tube 92
Glass tube 91 is arranged at intervals outside the
A TiO ₂ photocatalyst is provided on the surface of the glass tube 91 facing the quartz tube 92.

In this nitrogen oxide sampler 90, a sample gas is introduced into a gas flow path formed between a quartz tube 92 and a glass tube 91, a photocatalyst is activated by ultraviolet rays from an ultraviolet lamp 93, Nitrogen oxides contained in the gas are oxidized and collected, and the water is extracted for recovery.

In FIG. 6, reference numerals 94 and 96 denote pipes for introducing and extracting extracted water, reference numeral 95 denotes a pipe for introducing a sample gas, and reference numerals 97 and 98 denote pipes for introducing a purge gas and a purge gas and a sample. This is a gas outlet pipe.

[0006]

In the above-described nitrogen oxide sampler using the conventional photocatalyst, the efficiency of trapping and recovering nitrogen oxides is improved by activating the photocatalyst with ultraviolet rays. Requires
Therefore, there is a problem that it is difficult to reduce the size, and there is a problem in selecting a location for collecting the sample gas.

Accordingly, the present invention solves the above-mentioned problems of the conventional nitrogen oxide sampler, and enables efficient collection and recovery of nitrogen oxide by natural light without the need of an ultraviolet lamp, and also reduces the size. It is an object to provide a nitrogen oxide sampler which can be used.

[0008]

According to the nitrogen oxide sampler of the present invention, the sampler is formed in a flat plate shape, and by forming the sampler into a flat plate shape, a window portion for taking in external light such as natural light is formed. The photocatalyst is activated by the external light introduced through the section to collect and collect nitrogen oxides, thereby eliminating the need for an ultraviolet lamp and realizing miniaturization.

The nitrogen oxide sampler of the present invention has a flat plate-like base on which fine particles of a photocatalyst are fixed in order to make the sampler a flat plate shape and to take in external light such as natural light into an internal photocatalyst. A flat plate-shaped light-transmitting plate through which external light is incident and transmitted, and the light-transmitting plate is disposed facing the surface of the base where the photocatalyst is fixed at an interval, and is formed by the base and the light-transmitting plate The configuration is such that the gas flow path is formed by the intervals. In this configuration, the photocatalyst is activated by the external light transmitted through the light transmitting plate, and the nitrogen oxide in the sample gas introduced into the gas flow path is oxidized and collected.

According to the nitrogen oxide sampler of the present invention,
By arranging the flat plate-shaped base and the flat plate-shaped light-transmitting plate so as to face each other with a space therebetween, a flat plate-shaped collection surface can be formed. External light can be applied through a light-transmitting plate disposed opposite to the light-transmitting plate.
Thus, the photocatalyst can be activated by irradiating light without using an ultraviolet lamp, and the collection and recovery of nitrogen oxides can be performed. In addition, by eliminating the need for an ultraviolet lamp, external light such as natural light or illumination light can be used, and the size of the nitrogen oxide sampler itself can be reduced. Restrictions are relaxed, and the range of measurement sites for nitrogen oxides can be increased.

In the nitrogen oxide sampler of the present invention, as a fixing method for fixing the photocatalyst on the base surface, TiO ₂ / hydroxyapatite is applied on the base surface of Teflon or the like, and PTFE is used as a binder on the applied surface.
Spraying (polytetrafluoroethylene) film lubricant
Further, by spraying the TiO ₂ powder on the PTFE, the TiO ₂ photocatalyst can be fixed. This makes it possible to fix the photocatalyst to the flat plate-shaped base, and to prevent separation and flow of the photocatalyst due to introduction of the sample gas or the extraction water.

Further, in the nitrogen oxide sampler of the present invention, an introducing means for selectively introducing a sample gas and extracted water into a gas flow path of the nitrogen oxide sampler, and selecting the sample gas and the extracted water from the gas flow path. The continuous measurement of nitrogen oxides can be performed by providing the deriving means for deriving the extracted water, the analyzing means for analyzing the extracted water extracted, and the drying means for drying the gas flow path after discharging the extracted water. A nitrogen oxide measuring device can be configured.

[0013] According to this nitrogen oxide measuring apparatus, the sample gas is introduced into the gas flow path of the nitrogen oxide sampler by the introducing means, and the photocatalyst is irradiated with external light to capture the nitrogen oxide contained in the sample gas. Gather. After collecting the nitrogen oxides, switch the introduction means to introduce the extraction water into the gas flow path, elute the collected nitrogen oxides into the extraction water, take out the extraction water from the extraction means, and collect it in the analysis means Then, the nitrogen oxides are analyzed. The drying unit dries the gas flow path after extracting the extracted water, thereby collecting and recovering the next nitrogen oxide, and performing continuous measurement.

According to the embodiment of the present invention, it is possible to eliminate the need for an ultraviolet lamp, activate the photocatalyst by external light such as natural light or illumination light, and collect nitrogen oxides. Further, according to the embodiment of the present invention, by eliminating the need for an ultraviolet lamp, the nitrogen oxide sampler and the nitrogen oxide measuring device using the nitrogen oxide sampler can be miniaturized, and the sampling range can be reduced. Can be expanded.

According to the photocatalyst fixing method of the embodiment of the present invention, the photocatalyst of TiO ₂ can be fixed to a member such as Teflon easily and effectively without impairing the catalytic ability.

According to the nitrogen oxide measuring apparatus using the nitrogen oxide sampler of the embodiment of the present invention, it is possible to continuously measure nitrogen oxide.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 are diagrams for explaining the outline of a nitrogen oxide sampler according to the present invention. FIG. 1 shows each component of the nitrogen oxide sampler, and FIG. 2 is a plan view of the nitrogen oxide sampler. , Front view, and cross-sectional view.

In FIGS. 1 and 2, the nitrogen oxide sampler 1 has a flat plate-shaped base 11 on which fine particles of the photocatalyst 10 are fixed, and a first frame attached to the surface of the base 11 on which the photocatalyst 10 is fixed. The light-emitting device includes a portion 12, a second frame portion 13 attached to the first frame portion 12, and a light-transmitting plate 14 arranged to face the photocatalyst 10 on the base portion 11 with a gap. The base 11, the first frame 12, and the second frame 13
Can be formed of a material such as Teflon.

The base 11 is formed in a flat plate shape, and a photocatalyst is fixed on the upper surface thereof. FIG. 3 is a diagram for explaining fixation of the photocatalyst to the base. In FIG. 3A, a coating surface 10a of TiO ₂ / hydroxyapatite is formed on a base surface of Teflon or the like, and PTFE (polytetrafluoroethylene) is used as a binder on the coating surface 10a.
Is sprayed by a spray or the like. Furthermore, by sparging the TiO ₂ powder 10c photocatalysts in this film lubricant 10b upper, performs the fixing of the TiO ₂ photocatalyst.

Since the photocatalyst 10 formed on the base 11 is a portion for trapping nitrogen oxides, the trapping efficiency of nitrogen oxides is improved as the area of contact of this photocatalyst with gas is increased. The contact area between the photocatalyst and the gas is affected by the generation area of the photocatalyst generated on the base and the state of fixation of the fine particles of each photocatalyst to the base.

According to the nitrogen oxide sampler of the present invention,
It is possible to enlarge the contact area by increasing the generation area of the photocatalyst on the base and by the method of fixing the photocatalyst, reduce the contact area between the TiO ₂ powder particles and the film lubricant 10b photocatalyst Therefore, the contact area between the fine particles of the TiO ₂ powder of the photocatalyst and the gas can be increased.

The first frame portion 12 is a member having an opening 12a at the center, and forms a gas flow path together with the base portion 11 and the light transmitting plate. The second frame 13 is also provided with an opening 13 at the center.
a transparent window that guides external light to the inside by forming a light-transmitting plate 14 into the opening 13a. Further, the light transmitting plate 14 can be formed of, for example, quartz, and external light such as natural light or illumination light can efficiently reach the photocatalyst 10.

Further, a through hole reaching the opening 12a of the first frame portion 12 is formed in a part of the second frame portion 13, and a tube portion communicating with the through hole is formed. Mouth 15
And an outlet 16 are formed. The inlet 15 and the outlet 16 constitute a pipe for introducing a sample gas or extracted water into the gas flow path of the nitrogen oxide sampler, or for drawing out the gas from the gas flow path. FIG.
In the embodiment, the inlet 15 and the outlet 16 are provided on the opening 13a side of the window to which the light transmitting plate 14 is attached.
Conversely, it can be provided on the base side.

FIG. 2A is a plan view seen from the side indicated by the arrow A in FIG. 1, and external light is guided to an internal gas flow path through the opening 13a and the light transmitting plate 14 in the figure. , Photocatalyst 1
0 is activated to collect nitrogen oxides. FIG.
FIG. 2B is a front view seen from the length direction, and FIG. 2C is a cross-sectional view taken along the line BB ′. The sample gas or extracted water introduced from the inlet 15 flows in the gas flow path in the direction of the arrow in FIG.

The collection of nitrogen oxides by the photocatalyst involves, for example, the oxidation of nitrogen oxides by active species generated by electron excitation by light on the surface of TiO ₂ fine particles, and the adsorption of hydroxyapatite. Adsorption is performed. Thereafter, when an extraction water such as deionized water is contacted for a certain period of time, these nitrogen oxides are extracted as nitrite ions or nitrate ions. Therefore, by quantifying the nitrite ion or nitrate ion, the concentration of nitrogen oxide in the sample gas can be obtained.

Therefore, the nitrogen oxide sampler 1 in the form of a flat plate has a surface on which the photocatalyst 10 of the base 11 is provided and the light transmitting plate 1.
The sample gas introduced into the gas flow path is activated by external light incident through the light transmitting plate 14 while flowing through the gas flow path. The nitrogen oxides are oxidized and collected by contact with the oxidized photocatalyst.

Next, an apparatus for measuring nitrogen oxides using the nitrogen oxide sampler of the present invention and its operation procedure will be described with reference to FIGS.

In the nitrogen oxide measuring apparatus shown in FIG. 4, an analyzer such as an ion chromatograph 3 is connected to a nitrogen oxide sampler 1 and a valve and a pump are program-controlled to perform an automatic continuous measurement of the nitrogen oxide. It is a measuring device that can be used.

The nitrogen oxide measuring apparatus includes a nitrogen oxide sampler 1 of the present invention, and a sample gas collecting section 2 for collecting and collecting a sample gas, and a sample water collecting section 2 for extracting water collected by the sample gas collecting section 2. It is provided with a pump 62 for feeding liquid and an ion chromatograph 3 for measuring nitrate ions and nitrite ions in the extraction water. The ON / OFF control of the valves, valves, and pumps provided in each section can be performed by a control device (not shown).

The sample gas collection unit 2 includes a sample gas suction port 21 for sucking and introducing a sample gas, a standard gas generator 51 for generating a standard gas for calibration, and a sample gas or standard gas introduced. A three-way valve 31 for selecting and leading to the nitrogen oxide sampler 1, a flow regulator 22 for adjusting the flow rate of the selected gas, and extracting water into the gas flow path of the nitrogen oxide sampler 1 on which the sample gas or the standard gas is adsorbed. , A valve 42 for controlling the injection of extracted water from the extracted water injector 25, and a purge gas generator 52 for generating a purge gas for drying the gas flow path after discharging the extracted water. A valve 41 for controlling a purge gas from a purge gas generator 52; a sample gas or a standard gas from a flow rate regulator 22; A valve 32 for selecting the purge gas from the sampler and sending it to the inlet 15 of the nitrogen oxide sampler 1 and extracting water taken out from the outlet 16 of the nitrogen oxide sampler 1 to the ion chromatograph 3 to send the gas to the exhaust side A valve 33 for selecting for sending, a valve 44 for controlling the extraction water to the ion chromatograph 3, an extraction water measuring section 24 for measuring the flow rate of the extraction water, and a valve for controlling the exhaust gas 43, a mist trap 23 for removing moisture in the exhaust gas, and a suction pump 61 for gas suction.

FIG. 5 is a flow chart for explaining the measuring operation of the nitrogen oxide measuring device. The measurement of nitrogen oxides in the sample gas by the nitrogen oxide measuring device
Is switched to the sample gas inlet 21 side, the valve 32 is switched to the flow controller 22 side, and the sample gas is introduced from the sample gas inlet 21 into the nitrogen oxide sampler 1 (step S).
1) Irradiating the nitrogen oxide sampler 1 with external light such as natural light or illumination light to activate the photocatalyst and collect nitrogen oxides in the sample gas. The sample gas flowing out from the outlet 16 of the nitrogen oxide sampler 1 passes through the valve 33 and the valve 43 to remove water with the mist trap 23, and is then sucked and exhausted by the suction pump 61 (step S2).

After a predetermined amount of the sample gas has been introduced and the collection of the introduced gas has been completed, the valve 31 is closed, and
Is switched to the extraction water injector 25 side, the valve 42 is opened, and the extraction water is introduced into the gas flow path of the nitrogen oxide sampler 1 (step S3). When the extracted water is introduced into the gas channel,
The extracted water contacts the photocatalyst in the gas flow path. As a result, the nitrogen oxides oxidized by the photocatalyst and adsorbed as nitrite and nitrate are eluted as nitrite ions and nitrate ions in the extraction water (step S4). Thereafter, the valve 33 is switched to open the valve 44, and the nitrogen oxide sampler 1 is opened.
Extracted water from which nitrogen oxides have been eluted is taken out of the apparatus and introduced into the ion chromatograph 3 for measurement (step S).
5).

After the extraction of the extracted water is completed, the valve 32 is switched to open the valve 41, and the purge gas is supplied from the purge gas generator 52 into the gas flow path of the nitrogen oxide sampler 1 to dry the gas flow path. . Thus, the next nitrogen oxide trapping / collecting operation can be performed.

According to this nitrogen oxide measuring apparatus, the collection, recovery and measurement of nitrogen oxide can be performed automatically and continuously by controlling the control of valves, valves and pumps in a program. Since the nitrogen oxide sampler can activate the photocatalyst by external light,
It is possible to collect nitrogen oxides without using a conventional ultraviolet lamp.

In introducing the sample gas, a control valve capable of controlling the introduced volume can be used instead of the flow regulator. Further, by providing a heating device in the nitrogen oxide sampler, it is possible to speed up drying of the gas flow path.

The calibration can be performed by sending the standard gas instead of the sample gas to the nitrogen oxide sampler and performing the measurement in the same operation procedure as described above.

[0037]

[Table 1] Table 1 is an example of an experimental result using the nitrogen oxide sampler of the present invention, in which the flow rate was 0.2 L / min, the collection time was 30 minutes, and the amount of extraction water was 10 ml. It is a measurement of the recovery efficiency of nitrogen oxides. According to this, a recovery rate of almost 100% was confirmed.

[0038]

As described above, according to the nitrogen oxide sampler of the present invention, it is possible to efficiently collect and recover nitrogen oxide by natural light without using an ultraviolet lamp, and to reduce the size. Can be.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an outline of a nitrogen oxide sampler of the present invention.

FIG. 2 is a diagram for explaining an outline of a nitrogen oxide sampler of the present invention.

FIG. 3 is a view for explaining fixation of a photocatalyst to a base of the nitrogen oxide sampler of the present invention.

FIG. 4 is a schematic diagram for explaining an apparatus for measuring nitrogen oxides using the nitrogen oxide sampler of the present invention.

FIG. 5 is a flowchart for explaining a nitrogen oxide measuring apparatus using the nitrogen oxide sampler of the present invention.

FIG. 6 is a schematic view of a conventional nitrogen oxide sampler used for measuring the concentration of nitrogen oxide using a photocatalyst.

[Explanation of symbols]

1. Nitrogen oxide sampler 2. Sample gas collection unit 3.
Ion chromatograph, 10 photocatalyst, 11 base, 1
2, 13 ... frame part, 12a, 13a ... opening, 14 ... translucent plate, 15 ... inlet, 16 ... outlet, 21 ... sample gas inlet, 22 ... flow rate regulator, 23 ... mist trap, 24 ...
Extraction water measuring unit, 25 ... extraction water injector, 31, 32, 33
... valves, 41, 42, 43, 44 ... valves, 61, 62 ...
pump.

Claims (1)

[Claims] 1. A flat plate-shaped base on which fine particles of a photocatalyst are fixed, and a flat plate-shaped light-transmitting plate through which external light is incident and transmitted, wherein the base has a transparent surface with respect to a surface on which the photocatalyst is fixed. The light plates are opposed to each other with an interval therebetween, a gas flow path is formed by an interval formed by the base and the light transmitting plate, and a photocatalyst is activated by external light transmitted through the light transmitting plate, so that the gas flow path is formed in the gas flow path. A nitrogen oxide sampler characterized by collecting nitrogen oxides in an introduced sample gas.