JPH054023B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a device for measuring ozone dissolved in water. For example, underwater ozone measurement equipment can be used in rivers, lakes,
When water collected from groundwater systems is supplied as tap water, it can be used to monitor dissolved ozone after ozone oxidation treatment at water treatment plants, or to monitor dissolved ozone during ozone treatment in sewage treatment. . (Prior Art) Methods for measuring ozone in the atmosphere include an absorption photometry method using ultraviolet light and a chemiluminescence method, and devices using each method are commercially available. Absorption photometry using ultraviolet light is used to measure ozone in water (Analytical
Analytical Chemistry, No. 55
vol., pp. 46-49 (1983)). The absorption spectrum of ozone has a peak around 254 nm. For this reason, ozone measuring devices using the spectrophotometry method usually use a filter to use light with a wavelength around 254 nm from a low-pressure mercury lamp. Since the chemiluminescent measurement method utilizes a gas phase reaction, it cannot be immediately applied to the measurement of ozone in water. (Problems to be Solved by the Invention) Ozone measurement by spectrophotometry has low sensitivity. Furthermore, various ions coexist in water. Some of these coexisting substances, such as chromium ions (), manganese ions (), and phthalic acid, have an absorption coefficient equal to or higher than that of ozone for 254 nm ultraviolet rays.
Therefore, when trying to measure ozone in water by spectrophotometry, the coexisting substances interfere, making it impossible to accurately measure the ozone concentration. An object of the present invention is to provide a measuring device that can selectively and highly sensitively measure ozone with less interference from coexisting substances in water. (Means for Solving the Problems) The device of the present invention includes a permeation section that brings sample water into contact with a gas that does not react with ozone through a microporous organic or inorganic polymer membrane that does not react with ozone; It includes a reaction cell that causes the gas that has passed through the transmission section to react with ethylene gas, an ethylene derivative gas, or a nitrogen monoxide gas to emit light, and a detection means that detects light from the reaction cell. As the gas that does not react with ozone, air, nitrogen, rare gas, etc. can be used. Air may contain trace amounts of ozone, so when using air, it must be passed through an ozone decomposer using activated carbon or soda lime. (Function) When the sample water is brought into contact with a gas that does not react with ozone through the microporous polymer membrane in the permeation section, the ozone in the sample water passes through the microporous polymer membrane and moves into the gas. The gas that has passed through the permeation section will contain ozone in the sample water, so this gas is introduced into the reaction cell, and ethylene (C ₂ H ₄ ) is introduced into the reaction cell.
When gas, ethylene derivative gas, or nitric oxide (NO) gas is introduced, the ozone in the gas that has passed through the permeation section reacts with the ethylene gas, ethylene derivative gas, or nitric oxide gas to emit light. The chemiluminescence phenomenon caused by the reaction between ozone and ethylene gas, ethylene derivative gas, or nitrogen monoxide gas is well known. It is used as an ozone analyzer to measure ozone. Chemiluminescence between ozone and ethylene or ethylene derivatives emits continuous spectrum light in the wavelength range of 300 to 600 nm, while chemiluminescence between ozone and nitric oxide spreads over a wide range of 600 nm to 3 μm and 1.2 μm.
Continuous spectrum light with a peak is emitted. (Embodiment) FIG. 1 shows an embodiment of the present invention. Reference numeral 2 denotes a transmission section, and this transmission section 2 consists of a double tube consisting of an inner microporous Teflon (trade name of polytetrafluoroethylene, manufactured by du Pont) tube 4 and an outer Teflon or glass tube 6. There is. As the inner microporous Teflon tube 4, for example, Japan Gore-Tex's TB series (porosity 70%, maximum pore diameter 3.5 μm) is used.
and TA series (porosity 45%, maximum pore diameter 3.5μm)
etc. can be used. For example, TB002
has an inner diameter of 2 mm and an outer diameter of 3 mm. Since the length of the microporous Teflon tube 4 affects the sensitivity, it is used at an appropriate length. For example, the length
It is 50cm. Air as a first gas is supplied to the inside of the microporous Teflon tube 4 via an ozone decomposer 8. The ozone decomposer 8 has activated carbon 8a on the upstream side.
is filled, and the downstream side is filled with silica gel 8b. The ozone decomposer 8 is for decomposing ozone in the air. Sample water is flowed into the outer tube 6 by a suction pump 10. Air as a second gas is blown into the sample water by a pump 12 via an ozone decomposer 14. This ozone decomposer 14 is the ozone decomposer 8
is the same as In the permeation section 2, the sample water into which air is blown through the outside comes into contact with the air passing through the inside through the microporous Teflon membrane of the microporous Teflon tube 4, and the ozone in the sample water is transferred to the inside air. I will move to. The gas that has passed through the inside of the microporous Teflon tube 4 of the permeation section 2 is guided to the reaction cell 18 via the moisture remover 16. The moisture remover 16 is a double tube consisting of a Nafyon tube (trade name of du Pont) 20 with an inner diameter of 2 mm and an outer diameter of 3 mm, and an outer glass, Teflon or other plastic tube 22 with an inner diameter of 5 mm. The Nafion tube 20 is a sulfonated microporous Teflon tube, and has a dehydrating effect to selectively permeate moisture in the gas phase. Air drawn by the pump 24 flows through the filter 26 on the outside of the Nafhillon tube 20, and the gas that has passed through the permeation section 2 passes through the inside of the Nafhillon tube 20.
At this time, moisture in the gas passing inside the Nafhillon tube 20 is removed through the wall surface of the Nafhillon tube 20. Gas from the permeation section 2 is introduced into the reaction cell 18 via the moisture remover 16, and ethylene gas is also supplied to cause a chemical reaction with ozone in the gas to cause light emission. Pump 2 is installed in the reaction cell 18.
8 is provided for exhaustion. The light emitted from the reaction cell 18 is detected by a photomultiplier tube 30, and the signal from the photomultiplier tube 30 is guided to a recorder. Connections between the permeation section 2 and the ozone decomposer 8, between the permeation section 2 and the moisture remover 16, and between the moisture removal device 16 and the reaction cell 18 are made using Teflon tubes. If the pipe diameters between the parts to be connected are different, they can be connected using different diameter joints. As the gas introduced into the reaction cell to cause chemiluminescence with ozone in the gas introduced from the transmission section 2, an ethylene derivative gas such as isobutylene or dimethyl butene, or nitrogen monoxide gas is used instead of ethylene gas. It's okay. The appropriate flow rate of the gas introduced into the reaction cell 18 from the permeation section 2 is 0.1 to 2/min at atmospheric pressure. FIG. 2 shows the relative sensitivity when the length of the microporous Teflon tube 4 in the transmission section 2 is changed in this example. The microporous Teflon tube 4 is TB002, and the flow rate of air passing inside it is 0.6/min at atmospheric pressure, and the flow rate (atmospheric pressure) of air in the sample water passing through the outside is "air"/"sample water". ”=0.5. According to this result, as the microporous Teflon tube 4 becomes longer, the amount of ozone transferred from the sample water outside the microporous Teflon tube 4 to the gas inside increases, and the sensitivity increases. Recognize. FIG. 3 shows the change in sensitivity with respect to the flow rate ratio between the sample water flowing outside the microporous Teflon tube 4 and the gas (in this case air, atmospheric pressure) blown into the sample water. However, the microporous Teflon tube 4 is TB002, its length is 50 cm, and the flow rate of gas passing inside the microporous Teflon tube 4 is 0.6/min at atmospheric pressure. According to these results, it can be seen that as the amount of gas blown into the sample water increases, the sensitivity increases. Figure 4 shows the relationship between ozone concentration and relative sensitivity. The sensitivity shows linearity over a wide range of ozone concentrations. However, the microporous Teflon tube 4 is TB002, its length is 50 cm, the flow rate of air passing through the inside is 0.6/min at atmospheric pressure, and the flow rate of air (atmospheric pressure) in the sample water passing through the outside is " Air” / “Sample water”
= 0.5. In the low ozone concentration region (broken line area) in FIG. 4, there is a problem in the linearity of the ozone generation source itself. The ozone detection limit in this example was approximately 0.3 ppb when the signal-to-nozzle (S/N) ratio was 3. FIG. 5 shows a transparent section 32 in another embodiment. This transmission part 32 also consists of an inner microporous Teflon tube 4 and an outer Teflon tube 6, like the transmission part 2 in FIG. The sample water blown into the tube passes through the microporous Teflon tube 4, and the air as the first gas, which is led to the reaction cell via the moisture remover, passes through the outside of the microporous Teflon tube 4. 8 and 14 are ozone decomposers, 12 is a pump that blows air into the sample water, and 10 is a pump that flows the sample water. FIG. 6 shows a transmission section 34 in yet another embodiment.
represents. A plurality of microporous holographic fibers 36 are bundled, and sample water into which air as a second gas is blown through an ozone decomposer flows inside the holographic fibers 36.
Air is supplied as the first gas through the ozone decomposer and led to the reaction cell via the moisture remover, and flows through the outside of the reactor 6. In this case as well, the first gas may be allowed to flow inside the holofiber fiber 36, and the sample water into which the second gas has been blown may be allowed to flow outside. The material for the microporous hollow fiber 36 is preferably Teflon or cellulose acetate. In this embodiment, ozone is transferred from the sample water to the first gas through the microporous membrane of the holofiber fiber 36. FIG. 7 shows a transmission section 38 in still another embodiment.
represents. Sample water is passed through the tube 40, and air is blown into the sample water by a pump 44. The air blown by the pump 44 is supplied via an ozone decomposer. A probe 39 is inserted into the tube 40 downstream from the position where air is blown by the pump 44 . A microporous polymer membrane 42 made of Teflon or the like is provided at the tip of the probe 39, and tubes 39a and 39b are provided within the probe 39. The air supplied through the ozone decomposer is tube 39
a, flows along the microporous polymer membrane 42,
It exits from the tube 39b and is led to the reaction cell via a water remover. (Effects of the Invention) In the present invention, by bringing the sample water into contact with a gas that does not react with ozone through a microporous polymer membrane, ozone is transferred from the sample water into the gas.
Ozone was detected and measured using chemiluminescence method. As a result, in the present invention, ozone in water can be measured with high precision and high sensitivity. The table below shows the comparison results of the interference effects of coexisting substances when using the device of the present invention and when using the conventional ultraviolet absorption spectrophotometry (measured at 260 nm). The values in the table below are shown by replacing 1000 ppb of coexisting substances with ozone concentration (ppb).

【table】

[Table] Furthermore, even if the chlorine concentration is set to 70,000 ppb using the device of the present invention, the corresponding ozone concentration is
It was 1.6 ppb. In this way, in the device of the present invention, since interference by coexisting substances is extremely small, ozone in water can be measured with high precision.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a part of an embodiment of the present invention in cross section, Fig. 2 is a diagram showing the relationship between the length of the microporous Teflon tube and relative sensitivity in the same embodiment, and Fig. 3 is a diagram showing the relationship between sample water and relative sensitivity. FIG. 4 is a diagram showing the relationship between ozone concentration and relative sensitivity, and FIGS. 5 to 7 are schematic cross-sectional views showing the transmission part in other examples. It is. 2, 32, 34, 38...Transmission section, 4...Microporous Teflon tube, 6...Teflon tube, 16...Moisture removal device, 18...Reaction cell, 30...Photomultiplier tube, 36... ...Microporous holographic fiber, 42...Microporous polymer membrane.

Claims (1)

[Scope of Claims] 1. A permeation section that brings sample water into contact with a first gas that does not react with ozone through a microporous organic or inorganic polymer membrane that does not react with ozone; 1. A measuring device for ozone in water, comprising: a reaction cell that emits light by reacting the gas of No. 1 with ethylene gas, an ethylene derivative gas, or a nitrogen monoxide gas; and a detection means that detects light from the reaction cell. 2. The underwater ozone measuring device according to claim 1, wherein a second gas that does not react with ozone is blown into the sample water entering the permeation section. 3. The microporous polymer membrane is formed as a tubular body, the sample water flows outside the tubular body, and the first
The underwater ozone measuring device according to claim 1 or 2, wherein the gas flows inside the tubular body. 4 The microporous polymer membrane is formed as a tubular body, the sample water flows inside the tubular body, and the first
The apparatus for measuring ozone in water according to claim 1 or 2, wherein the gas flows outside the tubular body. 5. The underwater ozone measuring device according to claim 3 or 4, wherein a plurality of tubular bodies of the microporous polymer membrane are used in a stacked manner. 6 The microporous polymer membrane is attached to the tip of a probe in the permeation section, and the first gas flows within the probe along the microporous polymer membrane;
The apparatus for measuring ozone in water according to claim 1 or 2, wherein the tip of the probe is used by being immersed in sample water. 7. The underwater ozone measuring device according to claim 1 or 2, wherein a water remover is provided between the permeation section and the reaction cell.