JPS62215853A - Apparatus for measuring ozone in water - Google Patents

Abstract

PURPOSE:To make it possible to measure the amount of ozone in water with high accuracy and high sensitivity, by contacting specimen water with gas not reacting with ozone through a microporous polymer membrane. CONSTITUTION:Air is supplied into a microporous Teflon tube 4 through an ozone decomposition device 8 and the upstream side of the decomposition device 8 is packed with activated carbon 8a and the downstream side thereof with a silica gel. Specimen water is made to flow to an outside tube 6 by a suction pump 10 and ozone is blown in the specimen water by a pump 12 through an ozone decomposing device 14. In a transmission part 2, the specimen water passing the outside through the membrane of the microporous Teflon tube 4 and having air blown therein is contacted with air passing the inside and ozone in the specimen water moves to the inside. Air flows through a filter while being sucked through the outside of a Nafion pipe 20 by a pump 24 while the gas sent through the transmission part 2 passes the inside of the Nafion pipe 20 and, at this time, the moisture of the gas passing the inside of the Nafion pipe 20 is removed through the wall surface of the Nafion pipe 20.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for measuring ozone dissolved in water.

Water ozone measurement equipment is used to monitor dissolved ozone after ozone oxidation treatment at water treatment plants when water collected from rivers, lakes, underground water systems, etc. is supplied as tap water.
Alternatively, it can be used to monitor dissolved ozone in the ozone treatment process 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 Chemistry (A
Nalyt, 1cal Chemist, RY), Vol. 55, pp. 46-49 (1983)).

The absorption spectrum of ozone has a peak around 25 Jnm. For this reason, an ozone measuring device using the spectrophotometry method usually uses 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.

(Problem that the invention attempts to solve) Measuring ozone by spectrophotometry has low sensitivity.

Furthermore, various ions coexist in water. Among these coexisting substances, there are some, such as chromium ions (Vl), manganese ions (■), and phthalic acid, which have an absorption coefficient equal to or higher than that of ozone for 254 nm ultraviolet rays. Therefore, if an attempt is made to measure ozone in water by spectrophotometry, the coexisting substances will interfere, making it impossible to accurately measure 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 (C2H4) gas, ethylene derivative gas, or nitrogen monoxide (No) gas is introduced into the reaction cell. When introduced, ozone in the gas that has passed through the permeation section reacts with ethylene gas, ethylene derivative gas, or nitrogen monoxide 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 emits light with a continuous spectrum in the wavelength range of 600 to 600 nm.
Continuous spectrum light is emitted that spreads over a wide range of nm to 3 μm and has a peak at 1.2 μm.

(Example) FIG. 1 represents one embodiment of the invention.

Reference numeral 2 denotes a transmission section, and this transmission section 2 consists of a double tube consisting of an inner microporous Teflon (product name of polytetrafluoroethylene, du Pont) tube 4 and an outer Teflon or glass tube 6. ing. As the inner microporous Teflon tube 4, for example, Japan Gore-Tex's TB series (porosity 70%, maximum pore diameter 3.5 μm) or TA series (porosity 45%, maximum pore diameter 3.5 μm) is used. can do. For example, TBOO2 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, its length is 50 cm. 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 is filled with activated carbon 8a on the upstream side and filled with silica gel 8b on the downstream side. 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 same as the ozone decomposer 8.

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 water remover 16 is a Nafyon tube (du) with an inner diameter of 2 mm and an outer diameter of 3 mm.
Pont's product name) 20.

It is a double tube consisting of an outer glass, Teflon or other plastic tube 22 with an inner diameter of 5 mm. Nafyon tube 20
is a sulfonated microporous Teflon tube, and has a dehydrating effect because it selectively permeates moisture in the gas phase.

Air drawn by the pump 24 flows through the filter 26 on the outside of the Nafyon tube 20, and gas that has passed through the permeation section 2 passes through the inside of the Nafyon tube 20.

At this time, moisture in the gas passing inside the Nafyon tube 20 is removed through the wall surface of the Nafyon tube 20.

The reaction cell 18 is supplied with gas from the permeation section 2 through the moisture remover 16.
At the same time, ethylene gas is supplied to cause a chemical reaction with the ozone in the gas to cause it to emit light.

The reaction cell 18 is provided with a pump 28 for evacuation.

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 80, 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 Q/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 TBOO2, and the flow rate of air passing through its inside is 0.6Q1 min at atmospheric pressure, and the flow rate (atmospheric pressure) of air in the sample water passing through its outside is "air"/"
Sample water J = 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.

Figure 3 shows the sample water flowing outside the microporous Teflon tube 4 and the gas (in this case air, atmospheric pressure) blown into the sample water.
This shows the change in sensitivity with respect to the flow rate ratio. However, the microporous Teflon tube 4 is TBOO2, and its length is 50 cm.
, the flow rate of gas passing inside the microporous Teflon tube 4 is 0.6 Q/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 TBOO2, its length is 50 cm, and the flow rate of air passing through its inside is 0.00 cm at atmospheric pressure.
6 u/min, and the flow rate of air (atmospheric pressure) in the sample water passing outside the sample water is set to ``air j/sample water J = 0.5. There is a problem with the linearity of the source itself.The ozone detection limit in this example is approximately 0 when the signal-to-noise (S/N) ratio is 3.
．． It was 3 ppb.

FIG. 5 shows a transparent section 32 in another embodiment. This transparent section 32 is also the same as the transparent section 2 in FIG.

It consists of an inner microporous Teflon tube 4 and an outer Teflon tube 6, and sample water into which air as a second gas is blown passes through the microporous Teflon tube 4.

Air passes through the microporous Teflon tube 4 as a first gas, which is introduced into the reaction cell via a moisture remover. 8,1
4 is an ozone decomposer, 12 is a pump for blowing air into sample water, and 10 is a pump for flowing sample water.

FIG. 6 shows a transparent section 34 in yet another embodiment. A plurality of microporous holofibers 36 are bundled, and the inside of the holofibers 36 is passed through an ozone decomposer to a second
Sample water into which air as a gas is blown flows, and air as a first gas flows outside these hollow fibers 36, which is supplied via an ozone decomposer and led to a reaction cell via a moisture remover. It is configured as follows. In this case as well, the first gas may be flowed inside the holofiber 36, and the sample water into which the second gas has been blown may be flowed 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 36.

FIG. 7 shows a transparent section 38 in yet another embodiment. 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. Air supplied through the ozone decomposer enters through the tube 39a, flows along the microporous polymer membrane 42, and exits through the tube 39b.
It is led to a reaction cell via a water remover.

(Effects of the Invention) In the present invention, ozone is transferred from the sample water into the gas by bringing the sample water into contact with a gas that does not react with ozone through a microporous polymer membrane, and then the ozone is removed by chemiluminescence. detected and measured.

As a result, the present invention can detect ozone in water with high precision and
It becomes possible to measure with high sensitivity.

The case using the device of the present invention and the conventional ultraviolet absorption spectrophotometry method (2
The table below shows the results of a comparison of the interference effects of coexisting substances with the case measured at 60 nm). The numbers in the table below are coexisting substances 1000
The figures are shown with ppb replaced by ozone concentration (ppb).

Furthermore, even when the chlorine concentration is set to 70,000 ppb using the device of the present invention, the corresponding ozone concentration is 1.6 ppb.
Met.

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 drawings]

FIG. 1 is a schematic diagram partially showing an embodiment of the present invention in cross section;
Figure 2 is a diagram showing the relationship between the length of the microporous Teflon tube and relative sensitivity in the same example, Figure 3 is a diagram showing the relationship between the amount of air blown into sample water and relative sensitivity, and Figure 4 is a diagram showing the ozone concentration. FIGS. 5 to 7 are schematic cross-sectional views showing the transmission section in other embodiments, respectively. 2.32, 34.38...transparent part, 4...
... Microporous Teflon tube, 6 ... Teflon tube, 16 ... Moisture removal device, 18 ... Reaction cell, 30 ... Photomultiplier tube, 36...Microporous holofiber, 42...Microporous polymer membrane.

Claims (7)

[Claims] (1) A permeation section that brings the 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; An apparatus for measuring ozone in water, comprising a reaction cell that emits light by reacting 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 on the outside of the tubular body, and the first gas flows on the inside of the tubular body. The underwater ozone measuring device according to item 2. (4) The microporous polymer membrane is formed as a tubular body, the sample water flows inside the tubular body, and the first gas flows outside the tubular body. The underwater ozone measuring device according to item 2. (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) In the permeation section, the microporous polymer membrane is attached to the tip of the probe, the first gas flows inside the probe along the microporous polymer membrane, and the tip of the probe is placed in the sample water. The underwater ozone measuring device according to claim 1 or 2, which is used by being immersed in 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.